What is writing to Disk causing eventual Beach-ball-of-death
Please post the make/model/specs of your machine, and especially the brand, model and firmware revision of your SSD. I have an SSD that started throwing errors after 4,900 hours of operation. Updating the firmware resolved the issue. 

You can find the SSD firmware by running the Hardware Profile (or more info in About this Mac) and selecting Serial-ATA and the your SSD in the Device Tree.



Is the problem hardware or software?

I will attempt to list here a couple of possible issues, and what we need to help resolve.

If you have a second hard drive you can boot from (HDD, USB drive, etc.), please do. 


Does the problem still occur? 
If it does, does it happen on the boot device or still on the non-booted SSD? 
While booted from something other than the SSD, run any disk checking software you have, even if its just a Disk Utility/First Aid/Verify Disk




When did this problem start, and can you peg it to any action you did?

Wild process

Open Activity Monitor. First, click the drop list and change from My Processes to All Processes. Then click on the %CPU column header once (or twice) so the list shows the top CPU users at the top 



Is there a run-away process at the top? If so, please let us know.

Consistency after reboot

How soon after a reboot does the disk usage start? Do you reboot with the following option checked?



If you do, reboot, but first uncheck the option. 

Now that you're opening with a "fresh" login,


how soon after reboot does the problem start? 
Is there a consistency with any programs running when this happens?


Your problem can be a lot of things, but from your initial output, I'm less inclined to think malware.