System disk started to fail and hence I ran out to buy a new HDD 10 minutes before closing time :/ This is for a 32-bit system disk. From earlier, relatively long time ago, I had checked out Seagate Barracuda 2TB, but got convinced by the salesman to buy a 3TB WD Red NAS Harddrive as a lot of customers had returned Seagate disks with errors over the last months. Seagate in various colors. Went from 2TB to 3TB due to cost and my inkling to dive into that league  and force myself into GPT. NAS disks should be OK as OS disks, e.g. for this box that is up running 24/7 with a lot of activity as coding etc. (as in low I/O), no gaming, some media processing as converting cam cordings, rendering (though that is mostly done by cluster).My main question is regarding size of disk using various tools.(f)disk:#fdisk -l#disk -lDisk /dev/sdc: 801.6 GB, 801569726464 bytes255 heads, 63 sectors/track, 97451 cylinders, total 1565565872 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000lsblk:#lsblksdc      8:32   0 746.5G  0 disklshw:#lshw -class disk*-disk     description: SCSI Disk     physical id: 0.0.0     bus info: scsi@2:0.0.0     logical name: /dev/sdc     size: 746GiB (801GB)     configuration: sectorsize=512Why are they all yielding 764 GiB? Could there be any issues?As this would require GPT; any things I should be aware of / take extra caution with? E.g. any issues with 32-bit?S.M.A.R.T:Have done smartctl -t <conveyance|short> which both yield OK.SMART Self-test log structure revision number 1Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error# 1  Short offline       Completed without error       00%         0         -# 2  Conveyance offline  Completed without error       00%         0         -S.M.A.R.T also yield correct size (obviously):# smartctl --info /dev/sdcsmartctl 5.43 2012-06-30 r3573 [i686-linux-3.5.0-51-generic] (local build)=== START OF INFORMATION SECTION ===Device Model:     WDC WD30EFRX-68EUZN0Serial Number:    WD-XXXXXXXXXXXXLU WWN Device Id: X XXXXXX XXXXXXXXXFirmware Version: 82.00A82User Capacity:    3,000,592,982,016 bytes [3.00 TB]Sector Sizes:     512 bytes logical, 4096 bytes physicalDevice is:        Not in smartctl database [for details use: -P showall]ATA Version is:   8ATA Standard is:  ACS-2 (revision not indicated)Local Time is:    Sat Jan 10 18:40:58 2015 CETSMART support is: Available - device has SMART capability.SMART support is: EnabledNot much relevance but 1 hour usage of various tests etc. yield:Vendor Specific SMART Attributes with Thresholds:ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE  1 Raw_Read_Error_Rate     0x002f   100   253   051    Pre-fail  Always       -       0  3 Spin_Up_Time            0x0027   100   253   021    Pre-fail  Always       -       0  4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       1  5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0  7 Seek_Error_Rate         0x002e   100   253   000    Old_age   Always       -       0  9 Power_On_Hours          0x0032   100   100   000    Old_age   Always       -       1 10 Spin_Retry_Count        0x0032   100   253   000    Old_age   Always       -       0 11 Calibration_Retry_Count 0x0032   100   253   000    Old_age   Always       -       0 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       1192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       0193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       6194 Temperature_Celsius     0x0022   131   125   000    Old_age   Always       -       19196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0198 Offline_Uncorrectable   0x0030   100   253   000    Old_age   Offline      -       0199 UDMA_CRC_Error_Count    0x0032   200   253   000    Old_age   Always       -       0200 Multi_Zone_Error_Rate   0x0008   100   253   000    Old_age   Offline      -       0Sub question:If above OK, any other things that is smart to do before installing OS on disk?
Why my 3TB disk shows an actual size of ~800 GB with several tools except smart tools?
hard disk
If you're using a Debian-Ubuntu based system (like Linux Mint), then fdisk (util-linux 2.20.1) does not understand GPT.You should try parted -l and have you partitioned / formatted the drive yet? Using gparted (if you're using a GUI) would probably be easier.I'm not sure about lsblk, it says it reads from sysfs. It's possible there's only one small partition on the drive, or a strange MBR/GPT. But Cristian Ciupitu's comment and link from Seagate sound very promising, but it appears to be about Windows drivers...Searching for parted Error: /dev/sdc: unrecognised disk label brought up this link that appears to do what you'd like: How to Create Partition on Linux for >2TB Size using Parted GPT. I've bold-ed (embiggened?) the error message in question, looks like it should go away after creating a GPT. (I'll bet using gparted would be similar/easier.)Use parteds mklabel command to set disk label to GPT as shown below.# parted /dev/sdbGNU Parted 2.1Using /dev/sdbWelcome to GNU Parted! Type 'help' to view a list of commands.(parted) printError: /dev/sdb: unrecognised disk label (parted) mklabel gpt(parted) printModel: Unknown (unknown)Disk /dev/sdb: 5909GBSector size (logical/physical): 512B/512BPartition Table: gptNumber  Start  End  Size  File system  Name  Flags[Then it continues making a partition, but the above commands look the most relevant]Create >2TB Partition using Parted mkpartUse parteds mkpart command as shown below to create partition that is greater than 2TB. In this example, we are creating a partition that is roughly of 6TB in size.# parted /dev/sdb(parted) mkpart primary 0GB 5909GB(parted) printModel: Unknown (unknown)Disk /dev/sdb: 5909GBSector size (logical/physical): 512B/512BPartition Table: gptNumber  Start   End     Size    File system  Name     Flags 1      1049kB  5909GB  5909GB               primaryIf trying to create a GPT fails, there should be some good error messages to search. Or if it still only reports the size as 800GB, I'd begin to suspect there might be something wrong with the disk, but since SMART thinks it's ok, that leaves the linux drivers/kernel... And you're not using some sort of external USB enclosure are you? It's connected directly to the computer, like an internal HD?