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On my system (Debian), I can see the UUID identifier for all of my disks partitions (i.e. /dev/sda1, dev/sda2, ..)

ls /dev/disk/by-uuid/

However, I don't see the UUID identifier for /dev/sda itself. Is it possible to reference whole disk with UUID?

I need this because I want to reference a particular disk, and I cannot rely it will be called /dev/sda.

EDIT

The solution suggested by @don_crissti is great. However, I would like the UUID to be the same for all hard disks of the same Model/Manufacturer, not unique by serial number.

Using udevadm, I can see the disk attributes:

udevadm info -n /dev/sda -a
ATTRS{model}=="Samsung SSD 840 "
ATTRS{vendor}=="0x8086"
ATTRS{class}=="0x010700"
ATTRS{device}=="0x1d6b"
....

How can I generate a UUID from these attributes, so that same Model/Manufacturer disk will have the same UUID ?

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  • UUIDs are for filesystems, not partitions. There are PARTUUIDs for partitions, but nothing for whole disks. You'll probably have to write an udev rule to give /dev/sda a fixed name instead.
    – muru
    Commented Feb 18, 2015 at 21:18
  • 1
    What's interesting about this is there is now a UUID in the MBR (at least if it was created by Windows) but seemingly no way to use it.
    – Joshua
    Commented Feb 19, 2015 at 2:27

1 Answer 1

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The symlinks under /dev/disk/by-uuid/ are created by udev rules based on filesystems UUIDs. If you look at /usr/lib/udev/rules.d/60-persistent-storage.rules you will find entries like:

...... ENV{ID_FS_UUID_ENC}=="?*", SYMLINK+="disk/by-uuid/$env{ID_FS_UUID_ENC}"

To reference a disk you could use the disk serial number and the ENV{ID_SERIAL_SHORT} key.
The following udev rule matches the drive with serial no. 0000000013100925DB96 and creates a symlink with the same name under /dev/disk/by-uuid/:

KERNEL=="sd*", SUBSYSTEM=="block", ENV{DEVTYPE}=="disk", ENV{ID_SERIAL_SHORT}=="0000000013100925DB96", SYMLINK+="disk/by-uuid/$env{ID_SERIAL_SHORT}"

As to your other question... sure, you could always use ENV{ID_MODEL} instead of ENV{ID_SERIAL_SHORT} and use a custom string for your symlink name.
The following rule matches any drive with ID_MODEL = M4-CT128M4SSD2 and creates a symlink M4-SSD-1234567890 under /dev/disk/by-uuid/:

KERNEL=="sd*", SUBSYSTEM=="block", ENV{DEVTYPE}=="disk", ENV{ID_MODEL}=="M4-CT128M4SSD2", SYMLINK+="disk/by-uuid/M4-SSD-1234567890"

Note that this works fine as long as there's only one drive matching the ID_MODEL. If there are multiple drives of the same model, the rule is applied again for each of them and the symlink will point to the last detected/added drive.

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  • actually, I would like the UUID to be the same for all disks of the same Model/Type/Manufacturer. Do you happen to know what rule to use for that? Obviously not the serial number.
    – Michael Boies
    Commented Feb 19, 2015 at 16:04
  • please see my edit. What I am trying to accomplish: lets say my HDD breaks down, but I have replacement identical disk. I replace it and I would like to have same UUID as before (even though the serial number has changed). I do not intend to use both disk at the same time.
    – Michael Boies
    Commented Feb 19, 2015 at 16:20
  • @MichaelBoies - you can directly alter the UUID w/ gdisk - but I'm not sure if that's such a good idea. don - directly altering the links is a way better way to do it than actually altering the UUID - the computer would probably stop booting.
    – mikeserv
    Commented Feb 20, 2015 at 21:16

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