Btrfs Coming to Fedora 33 - <AUTHOR> https://fedoramagazine.org/btrfs-coming-to-fedora-33/ <comment><USER2> I've quickly skimmed the discussion on fedora-devel regarding btrfs. I wondered mainly how they'd handle the various cases where btrfs does not work well, e.g. files that change often inline (databases, VMs, etc). Apparently an application can tell to treat those files differently. So it's basically a matter of fixing various software to work nicely with btrfs as well as any similar filesystem. As mentioned in the thread, openSUSE already uses btrfs for loads of years. I do wonder why it isn't more supported by upstream software (postgres, VM things, etc).

I was also surprised how good the discussion was on fedora-devel. It seems that people didn't break into camps of "over my dead body", and "if we do not do this I'll leave", etc. It seemed more like a "this is my really thought out proposal, but is it actually feasible or did I forget anything". Then people raised problems, sometimes the proposer(s) already had a solution, sometimes it was something they didn't think of. What's nice is that despite seeing various problems everyone seemed to understand that people are trying to improve things.

I didn't read fedora-devel for many years so that was a welcome change over the past.

<comment><USER3> > _So it 's basically a matter of fixing various software to work nicely with > btrfs as well as any similar filesystem. I do wonder why it isn't more > supported by upstream software (postgres, VM things, etc)._

The concept of an application 'supporting a (specific) file system' sounds slightly ridiculous to me.

Why is Btrfs so special that apps should be rewritten for it? The always- compared ZFS seems to work just fine without alterations being necessary, so what make Btrfs worthy of extra considerations?

At most perhaps copy-on-write (COW) file systems _as a general class_ could perhaps be considered, as that may help with things like shingled drives and SSDs (i.e., zoned drives may be aligned with COW FSes).

<comment><USER4> > The concept of an application 'supporting a (specific) file system' sounds > slightly ridiculous to me.

Clearly you weren't around in the days when NFS was a thing.

<comment><USER3> > Clearly you weren't around in the days when NFS was a thing.

I was and am. I currently help admin an HPC environment with several petabytes of NFS storage.

And the main problems I've experienced with NFS have generally been with Linux locking. I've had a lot less drama with Solaris and BSD NFS (though I did uncover two Solaris NFS server bugs over the years).

Whenever I have NFS issues I generally start with the assumption that there's a bug in the NFS client code.

<comment><USER4> If you think applications work on NFS by just expecting general Unix filesystem semantics you're in for a surprise.

The fact you're not having trouble just means either the application writers put in the effort to properly support it, or your use case is simple enough not to run into problems.

<comment><USER3> > either the application writers put in the effort to properly support it

Given the hiccups that we've had with MySQL and locking, I'm not sure that's the case. (Less so with Postgres.)

I have only a moderate amount of knowledge of the applications that the dozen research groups use on the cluster, I just make sure the bits flow and haven't heard too many complaints over the years.

<comment><USER4> Clearly packages like MySQL and PostGreSQL made sure they work on NFS or they would very clearly tell you not to use it because they'd know it's a recipe for disaster. The issues I am referring to typically are with things like homegrown shell scripts or research software.

</comment></comment></comment></comment></comment></comment></comment><comment><USER5> btrfs has made some headlines in the past about its severely broken checksum computation in RAID modes, which rules them out for production use, i.e. [https://phoronix.com/scan.php?page=news_item&px=Btrfs- RAID-5...](https://phoronix.com/scan.php?page=news_item&px=Btrfs-RAID-56-Is- Bad)

 _The wrong parity and unrecoverable errors has been confirmed by multiple parties. The Btrfs RAID 5 /6 code has been called as much as fatally flawed_

It would be interesting to know if this has been addressed already.

The big fat red warning on btrfs' own wiki page is not inspiring trust either: [https://btrfs.wiki.kernel.org/index.php/RAID56](https://btrfs.wiki.kernel.org/index.php/RAID56)

 _For data, it_ should _be safe as long as a scrub is run immediately after any unclean shutdown_

<comment><USER6> It's interesting to see how Synology "solves" this problem: [https://www.synology.com/en- global/knowledgebase/DSM/tutoria...](https://www.synology.com/en- global/knowledgebase/DSM/tutorial/Storage/What_was_the_RAID_implementation_for_Btrfs_File_System_on_SynologyNAS)

<comment><USER7> Synology has solved it by running btrfs on top of mdraid, then patching it so that btrfs reports errors to mdraid and putting repair code into mdraid. This reliably works.

I'm sure some would be interested in this, but Synology seems to not take GPLv2 too seriously and nobody seems to care about this.

RAID 5/6 in btrfs is relatively neglected because the big users that pay developers to work on btrfs (and put the work up-stream) don't care that much about it. E.g. Facebook is probably using it for their HDFS storage, so HDFS gives them the RAID functionality.

<comment><USER8> They use it for everything except MySQL databases, which are stored on XFS.

There was a recent discussion on LKML where Chris Mason (I think) described all this.

<comment><USER9> Does XFS have better performance than ext4 for MySQL DBs?

</comment></comment></comment></comment></comment><comment><USER10> For desktop use, what problem does btrfs solve better than lvm+ext4?

Btrfs is slower than lvm+ext4, doesn't like working with large files, requires more ongoing maintenance (scrub, rebalancing), and is more prone to data corruption. Given that lvm can do snapshots under ext4, the only real benefit of btrfs is btrfs send, but for most use cases that doesn't seem like a large enough benefit to be worth the rest of brtfs' drawbacks.

<comment><USER11> > requires more ongoing maintenance (scrub, rebalancing)

I'm not sure that's a good description. Scrubbing is an option that you get extra. You don't need to use it and the behaviour won't be different than for example ext4 with regards to bad data detection. It's purely an extra feature.

If rebalancing is useful for desktop users (wasn't really in my experience), I'm sure it will get a system-provided job that balances the resource use and amount of reclaimed space.

<comment><USER12> There are concerns with ZFS of the "scrub of death" on a system lacking ECC ram:

[https://jrs-s.net/2015/02/03/will-zfs-and-non-ecc-ram- kill-y...](https://jrs-s.net/2015/02/03/will-zfs-and-non-ecc-ram-kill-your- data/)

There is some debate on this question:

[https://arstechnica.com/civis/viewtopic.php?f=2&t=1235679&p=...](https://arstechnica.com/civis/viewtopic.php?f=2&t=1235679&p=26303271#p26303271)

I'm curious if the situation is improved for BtrFS.

<comment><USER13> The first link actually explains why ZFS is no more dangerous than any other filesystem.

</comment></comment></comment></comment><comment><USER14> Interesting - As RHEL is downstream of Fedora, I thought BTRFS was not being explored further by Red Hat, on account of their deprecation of it downstream in RHEL.

If I recall this was because they didn't have the developers able to work on the software, preferring to use XFS + LVM to accomplish some of the goals of BTRFS as their STRATIS project.

I wonder what this means for RHEL going forward in RHEL 9?

<comment><USER15> It means nothing. This is only for the Fedora Desktop spin, and it's lead by the Fedora community not Red Hat.

<comment><USER16> _Disclaimer: I work for Red Hat but I have zero internal insight into this. I 'm just a happy Fedora desktop user_

I wouldn't say it means _nothing_ because Fedora is looked at as a proving ground for inclusion in RHEL, but I would agree that one shouldn't read much into it.

There are plenty of software packaged/supported on Fedora that isn't and won't be shipped in RHEL. BTRFS may or may not just be yet another one like that. I've heard/seen more excitement about Stratis (which does seem awesome so far) than I have btrfs.

</comment></comment></comment><comment><USER15> A few points:

\- No this doesn't affect RHEL.

\- It's only for Fedora Desktop spin (which for various reasons including this, but also others, you shouldn't use even on a Desktop - I install Fedora Server on my laptop).

\- Only a subset of btrfs features will be used, especially avoiding the ones which are known to be problematic.

<comment><USER17> Can you elaborate on the reasons for using Fedora server instead?

I use Fedora Workstation on several laptops and desktops (without issue). I'm curious if I'm missing some problem/opportunity.

<comment><USER15> Defaults to GNOME, firewall disabled, ext4 (and now btrfs) instead of XFS.

(These spins are all about defaults - so installing Server doesn't make it any less useful for desktops, but you may have to dnf install a few things the first time you use it.)

<comment><USER17> What do you mean "defaults to GNOME"? Server defaults to no DE at all I thought (been a year or two since I've used it) and Fedora defaults to GNOME anyway.

If it by default doesn't install email client and music players I don't use that might be nice though.

<comment><USER18> I think the defaults they're referring to are for fedora desktop, not server

<comment><USER17> Yes you're right - thank you. On a re-read I see that I had the assertions the wrong way round.

</comment></comment></comment></comment></comment></comment><comment><USER19> I have no issues with BTRFS, apart from the documentation is really poor.

I don't mind it becoming popular, but please for the love of $Deity can we please make the docs as good as ZFS. I will contribute cash if needs be.

Facebook are utterly shit at documenting things, so yes it might work for their usecase, but they essentially store knowledge through Shamanism, which is terrible unless you're inducted into the world of the spirits.

<comment><USER20> I for one support Facebook's push to make more problems solvable solely by entering a mud hut and ingesting hallucinogenics.

<comment> blaser-waffle That won't make them less evil, just less coherent.

<comment><USER19> Its only less coherent if youre not off your tits.

</comment></comment></comment></comment><comment><USER21> It's funny that fedora is moving to supporting btrfs as the default FS, when red hat has stopped supporting it altogether. I'm a big fan. In a world where we can't have GPL compatible ZFS, btrfs is the next best thing.

</comment><comment><USER22> There's probably no way to convert the legacy ext4+LUKS filesystem over, so, I guess I'll decide when F33 comes out whether I want BTRFS enough to do a clean install rather than an upgrade.

<comment><USER23> You can convert an ext4 filesystem to btrfs using btrfs-convert.

<comment><USER24> Is that stable?

<comment><USER25> Alright, so, disclaimer, I have lost data doing this but it was purely operator error! Closed my SSH session at the worst possible time. One of the podcast hosts at Linux Unplugged made the same mistake.

The btrfs-convert tool hypothetically leaves the ext filesystem all but untouched, and COW's the needed filesystem metadata onto the end of it, with data modifications coming thereafter (or intelligently stored within the free space of the ext system). You wait until you feel comfortable with BTRFS, then delete the preserved ext system and run a balance, which rewrites all data to disk in the usual structure. Alternatively, the preserved system can be restored, although I don't actually see instructions for that.

[https://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3](https://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3)

I love btrfs and would trust it but am glad to have backups of irreplaceable data.

<comment><USER22> I suppose I wouldn't need to worry about an SSH disconnect while working on localhost, but I'd still be a little concerned about trying it. I recently had a Pop!_OS/Ubuntu system irreparably damaged during an upgrade because the _lock screen_ come on during the five minutes I had stepped away from monitoring to use the bathroom.

The wiki also doesn't mention how well this process plays with LUKS, so, given how sensitive headers and such can be, I'll probably wait to hear from some F33 early-adopters on the conversion tool to see how it turns out. I'm reasonably happy with my ext4 system as it is, and most of my core data is on backup disks anyway, so I'm not sure how much the integrity checking of BTRFS would help. Seems like it would be more critical to have on the backup disks to make sure I'm not propagating the bit-rot.

</comment></comment></comment></comment></comment><comment><USER26> > The switch to Btrfs will use a single-partition disk layout, and Btrfs' > built-in volume management. The previous default layout placed constraints > on disk usage that can be a difficult adjustment for novice users. Btrfs > solves this problem by avoiding it.

good call, subvolumes came to the rescue of the /home partitioning. It's useful, but the inflexibility was in the proper split of available disk space. Novice users then saw warnings for /home - when there was still plenty of space on the root partition.

</comment><comment> 48bb-9a7e-dc4f2 It's painful to see how much disinformation (even in subtle ways or to go off the rails) some topics are getting in here.

If you want to get a better picture, also about Zfs and Fedora, read the previous Btrfs threads where the developers took the time to discuss it. And to kill some FUD.

I have no association with Btrfs or Fedora but I'd like to have a modern FS in-tree as battle tested as it can be.

</comment><comment><USER27> Surprising, I thought RH had drawn pretty clear lines in the sand in favor of evolving XFS to be the universal disk FS for Linux.

</comment><comment><USER28> Is btrfs still super slow at deleting large files?

It can take multiple seconds (like 5-10) on my fileserver to delete just one ~10GB file.

<comment><USER29> The 'rm' command should complete pretty quickly. Actually freeing up space takes time since a delete is subject to delayed allocation. The default transaction commit time is 30 seconds. And if there are snapshots or reflink copies, a backref walk is needed before extents can be freed.

<comment><USER28> I'm talking about the time it takes for the `rm` command to finish. I've started the habit of running all `rm` commands in the background on btrfs.

<comment><USER29> If it's reproducible, my suggestion is to strace the rm command and find out what it's doing that's taking so long; and post it to the mailing list:

[https://btrfs.wiki.kernel.org/index.php/Btrfs_mailing_list](https://btrfs.wiki.kernel.org/index.php/Btrfs_mailing_list)

<comment><USER30> Recording the kernel profile with perf would be more useful, I think. strace would probably only show long "unlink" syscall.

<comment><USER29> Yeah, and if perf is unrevealing, sysrq+t.

</comment></comment></comment></comment></comment></comment><comment><USER31> So how long until systemd-somethingmajor requires btrfs?

</comment><comment><USER32> I just herd my roommate saying "i don't want to play too much with my amd cpu overclocking because if i crash my system too much btrfs might get corrputed again".

 _laughs in zfs_

<comment><USER33> Don't worry, zfs has it's own share of problems.

I have one CentOS machine where I can't update ZFS from 0.7 to 0.8, if I want to boot again (zfs#8885).

<comment><USER34> Or switch distros.

I'm pretty sure I can't replicate this bug on Debian or Ubuntu.

<comment><USER35> That is like asking to move to a different house because you don't like the color of the walls.

<comment><USER34> To use that analogy, no, its more like moving to a different house because lead paint remediation is too costly and error prone.

<comment><USER35> That seems like an entirely different analogy and basically just says this apartment is bad, you should move. Then why did you move in in the first place?

The point is, you chose your distro for a reason and one little piece of software is far from enough to override that.</comment></comment></comment></comment></comment></comment>


Show HN: Spirit, modern django based forum software - <AUTHOR> http://spirit-project.com/ I finally got something worthy of posting here. Spirit is a modern forum software written on python employing django's framework.
It has many of the features available on more known solutions. It is easy to integrate to preexistent Django projects, since it works as any other app. I think it is worth a look for any Pythonist out there. Also, it has over 250 test cases!
Marketing site: http://spirit-project.com/ GitHub: https://github.com/nitely/Spirit <comment><USER2> If you are at an early enough stage to re-think the UI, one my my main gripes with existing forums is that when I hit reply they navigate me away to a login page. I mostly give up and close the tab. Instead of this, make the login form a simple popup, and log me in _in place_. Even make signup in place. You'll win hearts and users :)

<comment><AUTHOR> That would be a nice improvement! I'll get it done in the next release. Thanks, any suggestion is welcome ;)</comment></comment>


Zephyr: A scalable Real-Time operating system for IoT embedded devices - <AUTHOR> https://www.zephyrproject.org/ <comment><USER2> [https://www.zephyrproject.org/what-is- zephyr/](https://www.zephyrproject.org/what-is-zephyr/)

The Zephyr Project's goal is to establish a neutral project where silicon vendors, OEMs, ODMs, ISVs, and OSVs can contribute technology to reduce the cost and accelerate time to market for developing the billions of devices that will make up the majority of the Internet of Things

The Zephyr Project is perfect for building simple connected sensors, LED wearables, up to modems and small IoT wireless gateways. Because the Zephyr OS is modular and supports multiple architectures, developers are able to easily tailor an optimal solution to meet their needs. As a true open source project, the community can evolve the project to support new hardware, developer tools, sensor and device drivers. Enhancements in security, device management capabilities, connectivity stacks and file systems can be easily implemented.

The Zephyr kernel is derived from Wind River's commercial VxWorks Microkernel Profile for VxWorks. Microkernel Profile has evolved over 20 years from DSP RTOS technology known as Virtuoso. The RTOS has been used in several commercial applications including satellites, military command and control communications, radar, telecommunications and image processing. The most recent example of the technology's success is the successful Philae Landing on Comet Churyumov–Gerasimenko and the accompanying Rosetta Orbiter.

<comment><USER3> Zephyr seems like the best shot at getting an open source RTOS in safety- critical environments, pretty exciting.

<comment><USER4> I've been developing on Zephyr for about a year now and "exciting" isn't the word I would use here.

<comment><USER5> Can you tell us about your experience with it?

<comment><USER4> The build system is a mess. Recently switched from GNU make to CMake and it's still doing all kinds of weird stuff.

Uses Devicetree to configure drivers but doesn't use it like Linux, stuff gets munged into C #define macros and there's no runtime access like a DTB section.

Scheduler is still doing bad stuff, preemption is broken on certain architectures.

There is no mainline Cortex-A port yet. Some chipmakers have done it but won't share it.

Drivers are constantly in flux.

Ugh I could go on but won't.

I would label Zephyr as "FreeRTOS for when your boss says you can't use Linux."

<comment><USER6> Does that make FreeRTOS out to be FreeRTOS for when your boss says you can't use Amazon?

</comment></comment></comment></comment></comment></comment><comment><USER7> So I've contributed a couple of (tiny!) patches to Zephyr and wrote my own board support / devicetree setup for a custom Cortex-M4F setup that I designed.

Zephyr is awesome and the community is awesome, IMHO.

Using CLion to manage the CMake-based build is awesome.

What's not quite so awesome? The plethora of Kconfig items. Even with "make menuconfig" it can be very difficult to keep track of what you've configured in and what you've configured out.

For 90% of most projects, I'd expect the defaults to be sane. In fact, probably better than the ones an inexperienced dev would select.

But when you want that last 10%, it can be a real challenge.

I've had much more luck with Zephyr than I did with FreeRTOS or mbed (and I've used mbed a lot...)!

<comment><USER6> Total opposite. I'm having much more luck with FreeRTOS now that it's an Amazon product than I was with Zephyr. I'm using it with AWS though, so this isn't much of a surprise.

I'm not sure it'll go anywhere, but I think it's no coincidence zephyr is setting up to support multiple cores - and Nordic just released a dual core chip and signed on early to Zephyr.

<comment><USER8> Nordic signed on for Zephyr and Segger Embedded Studio.

Nordic clearly are signaling "we're tired of spending money on infrastructure software".

I hope they know what they are doing. IMO, the Nordic BLE stack was one of their primary competitive advantages.

<comment><USER6> Agreed! They insist they aren't dumping their stack (yes they are) but incorporating ideas in to Zephyr.

That said, they were definitely on the wrong track with SDKs that wildly changed every 6 months and were almost impossible to keep up with!

Their stack being FCC certified is a huge bonus. Saves weeks of work and $10,000 or so to not have to do full FCC cert instead of just emission testing.

As to Segger Studio, it's Rowley Crossworks and while I miss a couple of things from Keil it has been an overall better experience for some reason.

</comment></comment></comment></comment><comment><USER9> Is there an comparison to FreeRTOS and mbed? I could not find a good article online so far. There is a "Why create another RTOS?" section under [https://www.zephyrproject.org/what-is- zephyr/](https://www.zephyrproject.org/what-is-zephyr/) but it's very light on details.

<comment><USER10> I found this link ([https://www.osrtos.com/](https://www.osrtos.com/)) really useful 2 years ago. I don't know how up to date it is. In the end I went with a little known entry called TNEO because I liked Frank Dmitry's writup about it.

It's really hard to compare these things though. Zephyr is like a mini Linux complete with device tree, build system, configuration files and drivers. All of which you get to determine the correctness of.

Something like FreeRTOS can seem both much simpler and harder. It's mostly just C Source. If you need a stack or a driver, you get to own that yourself. But it's like, right there in front of you. No need to learn somebody else's favorite build system, etc. Do what makes most sense for you.

We went with TNEO because the ultimate feature we needed was aggressive processor sleep ability for power savings. I have not found any that solve this well out of the box. They're built for demo boards that stay plugged into the wall. And to be fair, there's a size-able chunk of IoT devices that sit near lots of power.

I asked a former coworker who helped me with TNEO (and before that he and I had worked quite a bit with FreeRTOS and RIOT as well as a lot of just no RTOS) how he's liking Zephyr in his new job. He said it was hell to set up and get working right, but the slack community around it had been helpful, but seemed to be nice at the moment, especially since they were using chipsets it was know to work well on. He did note that the power save story was no better than our previous experiences, but he's working on powered devices.

</comment></comment><comment><USER11> I think this is one of the OSes that PINE64 intends to support for their upcoming PineTime [https://wiki.pine64.org/index.php/PineTime](https://wiki.pine64.org/index.php/PineTime)

I wonder what's the development status, they were initially aiming to ship around Q1 2020.

</comment><comment><USER12> Still C... I have more hopes for Rust-written RTOS. Like Tock[1][2] or Drone OS[3][4].

[1] [https://www.tockos.org/](https://www.tockos.org/)

[2] [https://github.com/tock/tock](https://github.com/tock/tock)

[3] [https://www.drone-os.com/](https://www.drone-os.com/)

[4] [https://github.com/drone-os](https://github.com/drone-os)

<comment><USER13> I'm quite fond of the idea of single stack, rtfm and drone are particularly interesting!

I really appreciate the shared libraries in rust for soc support and Hal's. It's quite nice

</comment></comment><comment><USER13> Zephyr is quite nice and I've personally contributed some stuff, the general issues with it I think stem from IoT as a whole. People build products and move on to the next one. So sometimes drivers can be broken at times. It's still a RTOS and leads to common RTOS issues. The most frustrating to me is stack sizing. It's very easy to undersize a stack for a thread and not find out for quite awhile until something goes annoyingly wrong.

</comment><comment><USER14> It supports the esp32, but not the esp8266 :(

</comment><comment><USER15> > VxWorks

For me, this is enough to cross it out on day one.

C style tooling on proprietary MCU platforms is bad beyond any redemption.

Vx ecosystem has given me sooo much bad blood over the past decade. I have a lot of reservations about if just slapping an opensouce facelift on their SDK can right all its wrongs.

<comment><USER16> Contrary to your experience, VxWorks has a very good reputation in the embedded/real-time industry. I've used it in many projects myself.

It performs well, integrates well, runs on most things you can want and everything supports it. Its pretty much the de-facto standard in defence circles.

</comment></comment><comment><USER17> How does it compare to ARM Mbed OS?

</comment><comment><USER18> It is fun until you have to actually use it for development. Then it is not so much fun.</comment>


Facebook Generates 230,000 Jobs In Europe; Adds $15.3B To European Economy - <AUTHOR> http://digitizor.com/2012/02/04/facebook-european-economy/

<comment><USER2> Wait a minute,

1.nowhere in the article did the author, Shagun, identify where the 230,000 jobs were created.

2.The graph is out of place. The graphic shows the percentage of each countries populations belonging to Facebook. This has nothing to do with jobs or economic growth.

3.The article ended by repeating Facebook's mantra instead focusing on verification.

4\. The example of Burberry did not serve the article. It merely said Burberry gave away free items on facebook.</comment>


Pentagon official: FCC decision on 5G threatens GPS, national security - <AUTHOR> https://thehill.com/policy/defense/operations/496555-pentagon-official-fcc-decision-on-5g-threatens-gps-national <comment><USER3> I don't think there's enough detail here to decide whether or not to be mad. The L band is huge, 1000MHz-2000MHz. GPS uses a few tiny slices of this band. Cell phones, amateur radio, weather radar (though not precipitation-detection radar), ADS-B, and a ton of other non-military things are in that band. Adding 5G may or may not have any negative effect on GPS. I doubt they are proposing to run their 5G network on top of the GPS frequencies, after all, because everyone knows that would break GPS (which already operate well below the noise floor).

One time when we were working on testing Wifi interference, we tried to buy every possible 2.4GHz device to see what they did to our routers. We found these TV extenders (connect camera to one end, connect TV to the other) that claimed to be 2.4GHz but didn't interfere at all. We looked more closely with a spectrum analyzer and they were actually 1.3GHz and completely stepped all over the GPS frequencies. Did the FCC stop Amazon from importing these things? Nope. I guess my point is... the threat is real, but someone going out of their way to request permission from the government (as is legally required) is probably not going to cause many problems.

<comment><USER4> I'm not an RF person, but the way it was explained to me is that GNSS signals are in the neighborhood of 1560mhz-1610mhz. With the advent of GPSIII, even more of the important signals are getting pushed outwards towards the extremes of that range. Ligado/Lightsquared initially wanted permission to basically surround GPS (1526-1559mhz and 1610-1660mHz)

After lots of complaints, they amended their request to leave a buffer of 20mhz or so between their signals and GPS. However, Ligado wants to transmit at ~10watts, and the GPS signal is in the neighborhood of a _femtowatt_ by the time it hits a receiver. That can apparently still cause interference. For the GPS chip in your phone it may not make a huge difference. However testing has shown degraded performance in aviation GPS receivers more than a mile away from a 10watt transmitter. For even higher precision receivers (think surveyor equipment or maybe an autonomous tractor) the radius of the degradation stretches more than 2 miles from the transmitter. Ligado wants to put their transmitters ¼ of a mile apart.

Source for some of those numbers here, and an entertaining talk if you're ever able to see it in person: [https://rntfnd.org/wp-content/uploads/Brad-at-UAG- Users-Advi...](https://rntfnd.org/wp-content/uploads/Brad-at-UAG-Users- Advisory-Group-Oct-2019.pdf)

<comment><USER5> Why can't we just greatly improve the signal strength at source by an order of magnitude? Like I know the new satellites can use beam forming to increase power for some large area for military use but it looks like even so total power is about ~500W right now. What's stopping us from deploying 10KW sats?

<comment><USER6> > Like I know the new satellites can use beam forming to increase power for > some large area for military use

No, what you think you 'know' is plain wrong. Usually when discussing satellites, we're talking about a directional antenna that focuses a spot or wide beam for broadcast. A spot beam allows you to target a particular region, DirecTV uses spot beams to provide local broadcasts to general regions of the US. The military uses M-code shit on GPS with a directional antenna for the same sort of use case.

Beam forming is a different concept where you get creative with multiple antennas broadcasting at once and exploit signal cancellation to improve the data rate by shifting the phase between them. It does increase your received signal but relies on the receiver transmitting information back to the satellite (which is not going to happen for GPS, at least not the vast majority of consumer equip). Beam forming discussed on HN just last month: [https://news.ycombinator.com/item?id=22784132](https://news.ycombinator.com/item?id=22784132)

> What's stopping us from deploying 10KW sats?

Sat power is around and above that already, it doesn't make sense to increase the spot transponder ERP too much or you end up with issues like interference with adjacent bands since RF gets trickier to filter the higher the power it gets. Keep in mind a comm satellite usually has lots of transponders using maybe 100-500W each, so it adds up to some geosynchronous ones being like 20kW total consumption. Smaller LEO ones obviously not going to be close to that.

GPS released a paper about interfering with itself: [https://www.gps.gov/multimedia/presentations/2010/10/ICG/bet...](https://www.gps.gov/multimedia/presentations/2010/10/ICG/betz.pdf)

Communications history is littered with failure stories of people who wanted to throw power at the problem, when they only needed to find ways to listen better.

<comment><USER5> Thanks that's actually helpful. I did some more reading and it looks like it is as you say, the new military transmitters are directional and steerable, beam forming done on the receiving side.

But still it seems that power is still part of the solution given the increased power density of the new military antennas. I guess what I'm wondering is why they can't just reserve more band, move to regional antennas for whatever other technologies in addition to fighting polluters/jammers/spoofers and noisy neighbors. Or is that the plan?

</comment></comment></comment></comment></comment><comment><USER7> The history of lightsquared, the company involved, is horrendous. They bought spectrum with a SPECIFIC restriction on it to avoid GPS interference - <USER2> proceeded to get a proposal approved that violates that restriction. The amount of bad faith dealing by this company was eye opening.

I thought Garmin / Trimble and basically every GPS company had sued them because of how terrible their proposals and behavior has been.

This is not traditional 5G, it's basically misusing satellite spectrum.

<comment><USER8> It's more or less the same process where a developer buys land cheap and then with the help of a corrupt government rezones that land to something more valuable.

<comment><USER7> Not totally the same - its worse.

The FCC licenses bandwidth, no one owns it.

The FCC can rezone, they generally then run an auction, keep lots of $$ for the govt, and kick some back to others if needed especially if they force folks like TV stations to move their station broadcasts.

Lightsquared 100% lied when they said they would use the spectrum to serve 100% of users with a sat service. That was a necessary process for the original transfer (like for like use).

And the value they are getting is huge. 40MHz of nationwide bandwidth. Easily worth 10Billion plus.

Be totally fine for FCC to rezone using a normal process, auction to normal business at fair market value, protecting or compensating existing users.

</comment></comment></comment><comment><USER9> An interesting threat vector arises here for Huawei...

Ignore all the stuff about backdoors and such for a minute. I wonder if the administration fears that Huawai could simply attenuate their cell tower signals at a high wattage to disrupt all sorts of things.

I never thought of that before - "5G as a weapon".

Definitely a weird world. I need to start reading Judge Dredd again to start getting caught up on the future.

<comment><USER10> You might like Ghost Fleet [1] (or [2] for more colorful review). Ghost Fleet is essentially a white paper turned into a Tom Clancy style techno-thriller on what war might look like between China and the United States. Tactics from Ghost Fleet include:

\- Infected microchips from Chinese suppliers used to target and destroy the US Pacific fleet.

\- Disabling GPS with anti-satellite missiles.

\- Cyber attacks to disrupt the DOD communications networks.

[1]: [https://en.wikipedia.org/wiki/Ghost_Fleet_(novel)](https://en.wikipedia.org/wiki/Ghost_Fleet_\(novel\))

[2]: [https://morningconsult.com/2015/09/08/the-defense-wonks- who-...](https://morningconsult.com/2015/09/08/the-defense-wonks-who-just- killed-the-white-paper/)

<comment><USER11> Thanks for the recommendation.

> Infected microchips from Chinese suppliers used to target and destroy the US > Pacific fleet.

Awesome, the ideas that are often posted here have somehow made their way into fiction.

> Disabling GPS with anti-satellite missiles.

Just GPS? I'd expect surveillance and communications satellites to be much higher priority targets.

</comment></comment></comment><comment><USER12> FYI, Mark Esper (U.S. secretary of defense) has a commentary piece in today's edition of the WSJ about this, titled: "The FCC's Decision Puts GPS at Risk"

[https://www.wsj.com/articles/the-fccs-decision-puts-gps- at-r...](https://www.wsj.com/articles/the-fccs-decision-puts-gps-at- risk-11588719423)

</comment><comment><USER13> This is being framed as a military issue, but the reality is that this would cause havoc with aviation as well, especially precision GPS approaches.

Reminds me of a similar issue from 2012:

[https://www.gps.gov/news/2012/02/lightsquared/](https://www.gps.gov/news/2012/02/lightsquared/)

<comment><USER14> I'm a little worried that GPS is so vulnerable that these satellites could cause such disruption to be honest. This is satellite based, any country could be approving this plan and the impact on GPS would still be present since orbits go everywhere.

I guess I'd rather they just... not... I don't really even think the trade-off in increased seemingly real health risk is worth making the cell network even faster.

It's going to happen though, if there's no mitigation that makes GPS more invulnerable to interference it will inevitably fail when actually needed.

<comment><USER15> Let me just point out that satellites don't necessarily orbit around the world. They can be geostationary, and in fact they usually are I think. That is why you will find most US GPS satellites over the US, most Russian satellites over Russia, etc.

Also, signal disruption is already very common as a necessary precaution at sensitive times and places. I think many military bases and other sensitive places, like the Kremlin, have signal interference so they are very imprecise to target with GPS-guided weapons.

<comment><USER16> GNSS satellites (GPS, Galileo, GLONASS, Beidou, etc) are not in geostationary orbits. Being in a geostationary orbit would put them in fixed "locations" in the sky, making them easily blocked by terrain and entirely unusable at high latitudes.

GPS satellites are in MEO, at ~20 km MSL. Other GNSS satellites use similar orbits.

<comment><USER16> (Just noticed a minor error: GNSS orbits are roughly 20k km, not 20 km!)

</comment></comment></comment></comment></comment><comment><USER17> Is this even actually directly related to 5G? I mean a mobile phone can't connect directly to space satellite right?

The article says "Would allow telecom companies to deploy 5G networks". Is this satellite network for doing connnections between cell sites maybe?

If that's the case, it feels like 5G is only tangentially related and only included in story for click bait given that people seem to want to get mad about 5G recently.

<comment><USER18> Ligado (ex-lightsquare) product is a hybrid satellite terrestrial network. The specific component that people are concerned about is their terrestrial network which is very much a 5G creature (in so much at Ligado is marketing themselves and this approval as a step forward for 5G and IoT).

<comment><USER19> It's not a 5G issue, it's a spectrum allocation issue.

<comment><USER18> Fundamentally yes, but look at how both sides are trying to sell the issue. If Ligado and the FCC are both pushing this spectrum allocation issue as a question of helping 5G or not (and therefore hitching onto the we need 5G now or else China will beat us wagon), then I'm completely sympathetic to opposing coverage piling on the counter 5G bandwagon.

<comment><USER20> The counter 5G bandwagon seems to be largely comprised of conspiracy theories, dubious health claims, and unqualified assertions that people don't want more bandwidth. Why would you poison a legitimately important topic like spectrum allocation with associations like that?

<comment><USER21> Personally, I dislike how the conspiracy nonsense has kind of covered up the actual criticisms of 5g that existed prior to suddenly everyone thinking it's a great idea and if you don't, you're a conspiracy theorist.

I seem to recall this revolved around, questionable tangible benefits vs cost of deployment, poor penetration of 5g signals through structures, a lack of devices or internet plans to take advantage of 5g, and some other things that just seem to have taken a back seat to all the bullshit.

<comment><USER16> One has to wonder if some of the nonsense criticisms of 5G (causes disease, government conspiracy, etc) have been deliberately amplified to _drown out_ legitimate technical concerns.

<comment><USER22> Bingo...

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER23> I have yet to hear anyone who's not a telecom CEO or a politician say they actually _want_ 5G

<comment><USER24> I want 5G. There, you heard it. I'm not a telecom CEO and I'm not a politician.

Edit: I want fast, reliable telecommunications everywhere I go. I want ultra fast reliable telecom in crowded cities. I want cellular that is competitive with cable internet. I want bandwidth available for IoT devices.

<comment><USER25> > I want cellular that is competitive with cable internet. I want bandwidth > available for IoT devices.

It never will be though. Whatever frequencies you can do wirelessly you can do over a wire without the interference of other users using the same frequency at the same time.

Also a lot of promises 5G offers only sound good on paper. The higher frequencies don't travel well through walls (that's why it uses lower frequencies as well) and the maximum speed being talked can only be obtained during tests, but in the real deployment it has to be shared over all users.

Another problem is that the speeds don't mean sh*t if we have the same data caps, in fact higher speed is worse, because many applications will switch to a higher bitrate and consume more data, even when there's no noticeable difference on a phone.

<comment><USER26> >> I want cellular that is competitive with cable internet. I want bandwidth available for IoT devices.

> It never will be though. Whatever frequencies you can do wirelessly you can > do over a wire without the interference of other users using the same > frequency at the same time.

this is true in principle, but not necessarily in practice. I suspect it will hold for the near/medium future, but I can imagine a world where much more money is invested in improving mobile networks than home cable connections, causing the latter to stagnate.

most "normal" people I know don't even own a desktop computer. there are no devices in their homes that connect via ethernet (or even have an ethernet port without a dongle!). at a certain point, it might make sense to ditch the home modem/router altogether and scale up wifi networks to the point where they basically merge with cellular.

<comment><USER27> I agree the internet is increasingly carried over radio these days (e.g. WiFi, LTE, Satellite). Wireless still seems pretty young and crude yet. There seems to be plenty of room to grow with respect to negotiating power levels, frequency use, routing topologies and so on.

I think big fiber backhauls are still going to be a thing though.

<comment><USER26> > I think big fiber backhauls are still going to be a thing though.

absolutely, I'm just talking about wired vs. wireless as available to the typical consumer. the fiber would be the backhaul for an entire city block or neighborhood. just speculation.

</comment></comment></comment></comment></comment></comment><comment><USER28> I don't understand this. Is the DoD not subject to FCC regulation? Are there multiple bands that different types of GPS signals use (civilian vs military)?

My understanding of GPS was that it is used in _civilization critical_ applications like satellite synchronization and plane/ship navigation. How could any sane human approve an interference with this traffic?

<comment><USER29> >>Is the DoD not subject to FCC regulation?

That is complex, but most likely no. Like the FAA they largely respect the civilian agencies but ultimately they exist outside of that civilian regulation

>>Are there multiple bands that different types of GPS signals use (civilian vs military)?

Yes the military GPS is different from the Civilian GPS, the US DOD has the ability in a time of war to cut off Civilian access to the GPS Network where only US military (and approved Allies) receivers will work. This is one (of many) reasons the EU, Russia and China all have their own GPS systems

>>How could any sane human approve an interference with this traffic?

While I do not know if I agree (have not read enough on the interference to form a definitive opinion) the supporters of the new network claim there will not be any meaningful interference, that the DoD is over reacting and if there is Interference they will be required to replace the equipment..

<comment><USER30> > the military GPS is different from the Civilian GPS

I remember reading at some point that the civilian GPS was randomly offset so as not to give extremely accurate coordinates like the military GPS does. I thought that was interesting, if true.

<comment><USER31> The US used to intentionally degrade GPS signals available to civilian receivers as compared with those available to military ones, but it stopped doing that in the 1990s.

The biggest difference now between military and civilian GPS is that military receivers use two frequencies, whereas most civilian ones only use one (since using two costs more).

</comment></comment></comment></comment><comment><USER32> I struggle to see the point of 5G existing at all when I can already burn through the 22 GB data cap on my "unlimited" plan in an hour with 4G.

<comment><USER33> The new standard supports more concurrent users by using the available spectrum more efficiently. There are new modulation and timing "modes" that enable better coverage at cell edges and in dense urban environments. There is better support for multi-antenna systems which means better coverage and more efficient spectrum usage. End-to-end latency has been dramtically reduced and the next 5G NR iteration (rel 17) will add a super low-latency mode. There is now a mode for IoT that enbales low-power communication. Most of these changes aren't going to give you 1Gbps downlink speeds but they represent huge improvements over even LTE-A.

</comment></comment><comment><USER34> Is it correct to say that this impacts GPS not only for the American civilian and military but also the rest of the world?

What are other country's thoughts? It would be interesting to learn what led the FCC to make the decision they did... how did they deem the safety or consequences of this decision, etc. hopefully it's not driven purely by profit incentives that put lives at stake.

Disclaimer: I have no background on GPS, whichever wave "band" the issue impacts, or much of any technical understanding of the topic at all. Casual observer.

<comment><USER35> The company wants to build a 5G network in the US, so it would affect GPS in the US. It's interference at the receiver, not at the GPS satellites themselves.

<comment><USER36> My understanding of this is that the company wants to use L band, which is the designation for the range of frequencies in the radio spectrum from 1 to 2 gigahertz (GHz)

Doesn't 5G use higher frequency than that?

Is the company, a satellite company, trying to use their satellites to provide 5G or something? So if the interference starts at the satellites, it could affect other parts of the world?

>"We have presented to the FCC a proposal to utilize our terrestrial midband spectrum as a greenfield opportunity that is aligned with the commission's stated goals of providing the foundation of the 5G future," explained Doug Smith, Ligado president and CEO. "By deploying 40 megahertz of smart capacity on midband spectrum, we can create a model of at least a partial 5G network — a next-generation, hybrid satellite-terrestrial network — that will enable 5G use cases and mobile applications that require ultra-reliable, highly secure and pervasive connectivity."

<comment><USER37> 5G is a very broad term, which is supposed to offer 10x performance in all metrics over 4G.

This seems to be the same issue when they were called Light Squared. The L-band was to be used for terrestrial base stations with very high power transmitters. The issue is that, even though several MHz away, from the GPS carrier, the transmissions will compress the LNA on GPS receivers with poor or little filtering, desensitizing the GPS receiver.

Most civilian stuff now has decent filtering prior to the LNA so it can co- exist with all the other wireless crap crammed in your phone.

I'm an RF EE and do a lot with GPS.

</comment></comment></comment></comment><comment><USER38> See document FCC-20-48 [1] for full text. Some quotes:

 _" Our decision authorizes Ligado to deploy a low-power terrestrial nationwide network in the 1526-1536 MHz, 1627.5-1637.5 MHz, and 1646.5-1656.5 MHz band (...)"_

 _" Our action provides regulatory certainty to Ligado, ensures adjacent band operations, including Global Positioning System (GPS), are sufficiently protected from harmful interference (...)"_

 _" Ligado's amended license modification applications significantly reduce the power levels of its operations from its earlier proposals and commit Ligado to providing a significant guard-band in the MSS spectrum to further separate its terrestrial transmissions from neighboring operations in the Radionavigation-Satellite Service (RNSS) allocation. Based on the extensive record, we conclude that Ligado's latest proposal—combined with the stringent conditions we adopt today—addresses harmful interference concerns with respect to GPS operating in the adjacent RNSS allocation, as well as concerns with respect to MSS licensees' operations in the L-band."_

Read section "II. Background" for more technical info and changes since the LightSquared proposals.

[1] (PDF) [https://docs.fcc.gov/public/attachments/FCC-20-48A1.pdf](https://docs.fcc.gov/public/attachments/FCC-20-48A1.pdf)

</comment><comment><USER39> > ... and to repair or replace at Ligado's cost any government device shown to > be susceptible to harmful interference.

Boy, if that's the actual text (it isn't) of the contract, they need new lawyers.

</comment><comment><USER40> There also seems to be concerns that 5G may interfere with weather satellites: [https://www.nature.com/articles/d41586-019-03609-x](https://www.nature.com/articles/d41586-019-03609-x)

</comment><comment><USER41> While sometimes considered controversial for decisions made on intangible things like net neutrality, I expect the FCC would have a much better understanding of the electromagnetic spectrum than the military, and having all of them approve this tells me they see no threat to GPS from Ligado's spectrum use. Makes me wonder what the politics are behind this, especially when I see someone like Jim Inhofe involved.

<comment><USER42> >I expect the FCC would have a much better understanding of the electromagnetic spectrum than the military

Why? The FCC is concerned with coordinating peaceful use of commercial RF products (and experimentation that could lead to new commercial products). The military operates in hostile RF environments, conducts Signals Intelligence, and has to mitigate signal intelligence conducted against them. The demand for the absolute cutting edge of RF expertise is all on the military side.

</comment></comment><comment><USER43> I have not read up on it - I am no expert. However, this is the second technology (first being weather radar) that 5G is reported to have significant, negative effects on.

As a layman, I do wish we banned 5G entirely, assuming these assertions are correct. There is a greater public interest than even faster cell connectivity.

The wiki on 5G isn't bad - I now get that it is a tri-band negotiation, and I assume it is the "high" band that causes the issues.[1]

How does Wifi 6 use the same spectrum as 5G mid, but get such higher throughput?

And if the point of 5G is also to give higher speeds and capacity in dense urban environments, with denser antenna coverage, why couldn't they adapt the existing 2-6 GHz range instead of going up toward millimeter?

[1] - [https://en.wikipedia.org/wiki/5G](https://en.wikipedia.org/wiki/5G)

meta-edit: So, I put forward assertions, admitted humility and lack of expert knowledge, asked questions and linked to a wiki that I found to talk about the subject. If the person/people who downvoted me for the original content sees this, please note that the downvote button is not a disagree button. If you have substantive issue with the post, rebut it.

<comment><USER44> The problem has nothing to do with 5G inherently, and the vast majority of the bands it is approved to operate on will have no interference issues. The problem is that the current FCC has been very bullish on opening up more bands for mobile use even if there are legitimate interference concerns.

> And if the point of 5G is also to give higher speeds and capacity in dense > urban environments, with denser antenna coverage, why couldn't they adapt > the existing 2-6 GHz range instead of going up toward millimeter?

They are. Eventually all the bands currently used for 4G will be migrated to 5G. If you see T-mobiles ads about the largest 5G network in the country, that is all deployed on existing bands that were also approved for 4G. On these bands 5G will be a minor upgrade.

The millimeter bands are intended to significantly increase the number of concurrent users, but the places where it can be effectively deployed are very limited. It won't pass through buildings, and has short range. As an example, Verizon couldn't even cover a full sports stadium with a single tower, and that's a prototypical case of where millimeter is supposed to be valuable.

This latest issue is completely separate. It is entirely about a single company, Ligado, that bought spectrum adjacent to GPS at a discount deal because it came with strict restrictions on how that spectrum could be used to avoid interference with GPS. For years they have been trying to get the FCC to relax those restrictions for various different purposes, and this FCC finally approved. For previous requests there was tons of hard data filed showing that the proposed use would absolutely cause interference, and the requests were rejected. The latest approval does stipulate much wider guard bands and other measures to decrease interference. I don't know whether these measures are sufficient. The FCC commissioners unanimously think they are, while the DoD brass is insistent that they aren't.

</comment></comment><comment><USER45> Couldn't the FCC just rescind approval if there's interference with GPS? Or at least, with DoD GPS?

</comment><comment><USER46> >U.S. Space Force Gen. John Raymond told the Senate Armed Service Committee

>U.S. Space Force Gen.

I know it's unrelated, but it is very strange seeing this title actually written out.

<comment><USER47> "the Fourteenth Air Force/Air Forces Strategic was redesignated as Space Operations Command (SpOC)."

Because of course the Space Force would have something named Spoc(k).

[https://en.wikipedia.org/wiki/United_States_Space_Force](https://en.wikipedia.org/wiki/United_States_Space_Force)

</comment></comment><comment><USER48> Do they ever _not_ say that?

News would be "Pentagon official admits that <thing> doesn't actually threaten national security of largest military on the planet."

</comment><comment><USER49> It's in the military's interest to limit the freedom and empowerment of the public as much as possible. I would take their opinions with a grain of salt.

With that said, this seems like something that can be easily solved with technology improvements.

<comment><USER50> Excepting in this case where the military operates a critical, life-safety infrastructure used by civilians.

I'm frankly more concerned with the FCC acting as a taxpayer-funded telecoms industry cheerleader.

Dear FCC: You're regulators. You're supposed to be regulating. This is what you get for being public servants.

<comment><USER49> Meh, the military engages in far more life terminating than life saving.

<comment> kube-system Deterrence is hard to measure, but US military superiority correlates with a period of relatively low global conflict.

<comment><USER49> Maybe so, but the evidence is weak at best. Some wars (like Iraq, Korea, Vietnam) were a sham. I'd feel more comfortable knowing nobody had nuclear weapons.

<comment> kube-system You'd feel more comfortable, but is that the same as actually being safer?

<comment><USER49> You could ask someone who was living in Japan in 1945.

<comment><USER51> Or someone living in Nanking in 1938.</comment></comment></comment></comment></comment></comment></comment></comment>