Can you help me find UUID of my SSD which is partitioned already? The goal is I want to mount this SSD under my home dir. To do so, I need to add a line to my /etc/fstab file. To do so, I need to put its UUID in the line. To do so, I need to determine its UUID. Nothing is output by command blkid, which baffles me. The advice in the fstab file says:

" Use 'blkid' to print the universally unique identifier for a device"

and I certainly have this device, and this device is certainly working, and certainly partitioned, and I used sudo, but blkid steadfastly won't print anything about this device's UUID for some reason. But maybe the UUID is already being shown in the file /etc/fstab as UUID=69A1-BD52 so I don't really need blkid to work, and I can skip that nonsense. Not sure. OS is Ubuntu 14.04LTS.

Here is my current fstab:

# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
/dev/mapper/ubuntu--vg-root /               ext4    errors=remount-ro 0       1
# /boot was on /dev/sda2 during installation
UUID=9b4fb887-5dd8-413c-b0b0-dd3c803cf4ab /boot           ext2    defaults        0       2
# /boot/efi was on /dev/sda1 during installation
UUID=69A1-BD52  /boot/efi       vfat    umask=0077      0       1
/dev/mapper/ubuntu--vg-swap_1 none            swap    sw              0       0
/dev/nvme0n1 /mnt/fastssd auto nosuid,nodev,nofail,x-gvfs-show 0 0
# Following was added by ga for permanent fast swap file on ssd with high priority as created at cmd line earlier
/mnt/fastssd/100GiB.swap none swap sw 0 0

Here is output of df command:

$ df
Filesystem                   1K-blocks      Used  Available Use% Mounted on
udev                          65956452         0   65956452   0% /dev
tmpfs                         13196096      9816   13186280   1% /run
/dev/mapper/ubuntu--vg-root 1789679056  27183296 1671562308   2% /
tmpfs                         65980460         0   65980460   0% /dev/shm
tmpfs                             5120         4       5116   1% /run/lock
tmpfs                         65980460         0   65980460   0% /sys/fs/cgroup
/dev/nvme0n1                 492128608 104929192  362177652  23% /mnt/fastssd
/dev/sda2                       483946    250653     208308  55% /boot
/dev/sda1                       523248      3668     519580   1% /boot/efi
tmpfs                         13196096         0   13196096   0% /run/user/1000

Here is me running blkid to try to see the UUID:

$ blkid /dev/nvme0n1
$ blkid /mnt/fastssd
$ sudo blkid /mnt/fastssd
$ blkid /dev/sda1

Nothing outputted. I did not omit any output. My sudo login was successful.

This device is already partitioned and formatted and working nicely. Shouldn't every partitioned device already have a UUID?

Is UUID=69A1-BD52 its UUID? Can I confirm this?

Most important question: Can I safely repeat the UUID=69A1-BD52 in the new line I wish to add to my fstab file, so it will mount this SSD under my home directory?

Example of line I would add to my fstab if it's safe and correct to do so:

UUID=69A1-BD52  /home/user/fastssd auto   rw,noauto,user,sync          0  2

The above line is just a big guesstimate, and I don't know if 2 belongs there etc.

This device would be mounted twice. Is it safe or do I need to remove a line? I don't have a reason to keep the old mount location if the new mount location is OK. Would I need to change my SSD swap file entry if I move it to being under my home directory? It's OK by me for this device to be inaccessible to other users, as its my computer.

  • 4
    Type blkid without any arguments. Also the output of lsblk can be helpful as well.
    – 111---
    Dec 8 '16 at 15:04
  • @datUser: sudo blkid with no parameters returned the uuid, thanks. To mount it under the home dir can I just add a line to fstab or do I also need to delete a line from fstab so its not double-mounted? Does double mounting the same device hurt anything? And will my other line for the swap mount to this ssd need changing if I delete the old line from fstab? thanks. Dec 8 '16 at 15:49

Edit: As it turns out, the OP actually had a filesystem made on the unpartitioned SSD.

You probably don't want to mount the SSD. Probably you want to mount a partition on the SSD. To list the UUIDs of partitions:

sudo lsblk -o name,mountpoint,size,type,ro,label,uuid

Example result:

$ sudo lsblk -o name,mountpoint,size,type,ro,label,uuid
NAME                  MOUNTPOINT  SIZE TYPE  RO LABEL           UUID
sda                                40G disk   0                 
├─sda1                /boot       286M part   0 SERVERAX-BOOT   2db37cbc-6c0cb-4833-4511-3476aabf55d
└─sda2                           39.7G part   0                 2148212e-3652d-4c16-8115-2230b7c98a7
  └─Serverax                     39.7G crypt  0                 BU961-FLmD-mXHQta-VUkW-xPAQ-2H4D-vubDr
    ├─Serverax-Swap   [SWAP]      1.7G lvm    0 SERVERAX-SWAP   bef1e619-85a9a-44eb-43fd-c404b4fdc8a
    ├─Serverax-System /            20G lvm    0 SERVERAX-SYSTEM c0a7b4d2-a6515-436d-e10f-bca5a2340ef
    ├─Serverax-Home   /home        10G lvm    0 SERVERAX-HOME   8f410236-4e4c8-45f4-ab15-a8398dfa6fa
    └─Serverax-Srv    /srv          6G lvm    0 SERVERAX-SRV    0ceb5cd2-937e8-4c75-d4c4-67d5a10168f
sr0                              1024M rom    0                 

If you can, it is better to set your terminal to 132 columns before running the command.

  • Ooh nice output, thanks for this command. It still says type=disk not type=part so I'm still confused. There is no other line appearing regarding this ssd, such as something saying type=part for the partition that is definitely on that thing. I just copied a file to it, despite not having a type=part on that bugger. Look: nvme0n1 /mnt/fastssd 477G disk 0 fastone 7e3f91f2-2395-4018-b4fe-16bd7e644047 Dec 8 '16 at 15:56
  • Maybe you have formatted the disk and not partitioned it? What does sudo file -s /dev/sdx (with /dev/sdx replaced with the SSD disk device, of course)?
    – AlexP
    Dec 8 '16 at 15:57
  • Can I mount a disk that is not partitioned? Because I think, actually I know, I mounted it -- /mnt/fastssd is operational. So maybe I do want to mount the disk not the partition. what you think Dec 8 '16 at 15:59
  • Partitioning is a way of dividing the disk into independent sub-disks. Linux doesn't care for the difference between a full disk and a partition. You won't be able to partition it later, though.
    – AlexP
    Dec 8 '16 at 16:01
  • if you give my Q an upvote, I will give you the accepted answer to the nominal question in my title. However I am still left with unresolved question or 2 about fstab which is the ultimate goal of this inquiry (see above). thank you Dec 8 '16 at 16:11

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