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It is important to know a position of a bad drive in a multi-bay device, however default naming of drives e.g /dev/sda, /dev/sdb etc. does not provide a clue where a particular drive is residing physically.

I have an 8-bay external JBOD enclosure used for backup. It hosts a ZFS pool and is connected to an Arch Linux box. Is it possible on a Linux system which uses systemd/udev to name drives according to their physical location in the enclosure instead of /dev/sd*?

I would like the names to reflect the physical position of a drive in the enclosure /dev/encl1, /dev/encl2... or similar. I would prefer these labels to appear by default instead of /dev/sd* in lsblk and zpool status.

I do know location of every drive in the enclosure, and keep this information in a file, but it would be way better to see it with lsblk and other commands directly.

I tried to create rules at /etc/udev/rules.d like

SUBSYSTEM=="block" KERNEL=="sd*" ENV{ID_SERIAL_SHORT}=="ZR5CTR4V" SYMLINK+="encl1"

And I do get such symlinks after running udevadm trigger, but they are not equivalent to /dev/sd* and I was not able to use them as a substitution.

dimus
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  • There are *already* names that are more informative than `/dev/sd*`. Take a look at `/dev/disk/by-id/` and the other directories under `/dev/disk`. – larsks Jan 07 '23 at 14:43
  • @larsks, my specific usecase it to know the position of a drive in the enclosure by its name, so I can find it quickly in case of trouble. – dimus Jan 07 '23 at 15:38
  • How about the `by-path`? – vidarlo Jan 07 '23 at 15:46
  • @vidarlo, `by-path` still does not allow to tell that this particular drive is for example located 2nd from the top in the enclosure – dimus Jan 07 '23 at 15:47
  • Can you use `lshw -c disk -c storage | grep -E 'bus info|logical name` to give you a hint on the disk bays? I expect that the bus info will be incrementing uniformly following the bay numbers. – doneal24 Jan 09 '23 at 17:00
  • @doneal24, very cool command, I did not know about it! Actually, in my case, I do know positions of each drive, and I just keep this information in a file, but it is much less convenient than directly seeing this information by running `lsblk` for example. I edited question to clarify this. – dimus Jan 10 '23 at 01:30

2 Answers2

3

Writing up my comment as an answer.

Use the command

lshw -c disk -c storage | grep -E 'bus info|logical name’

to map device names to pci devices. The device id’s will increment uniformly, with the lowest id for bay 1.

You can also use udevadm to get the device id in devices.

udevadm info --name=/dev/nvme6

You can now give the disk devices names corresponding to the physical slot they are installed in. Edit or create /etc/udev/rules.d/my.rules. You can rename the device with the rules.

KERNEL=="nvme*", SUBSYSTEM=="nvme", ENV{PHYSDEVPATH}=="*pci0000:20/0000:20:01.3/0000:25:00.0*", NAME="bay6"
KERNEL=="nvme*", ENV{DEVTYPE}=="partition", SUBSYSTEM=="nvme", ENV{PHYSDEVPATH}=="*pci0000:20/0000:20:01.3/0000:25:00.0*", NAME="bay6p%n"

If you have sd devices instead or nvme, change the SUBSYSTEM to block.

It's possible to put in an alias instead of renaming the device. Look at SYMLINK+="bay6" in the udev documentation.

doneal24
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  • in my case it is already known where drives are located in the enclosure, the question is how to show this information conveniently in the name of the drives. For example `multipath` does it well by creating an `alias` to `wwid` data, and this alias appears as the default name for a drive – dimus Jan 10 '23 at 01:48
  • @dimus Added device renaming to my answer. – doneal24 Jan 10 '23 at 13:24
  • Thank you for expansion of your answer @doneal24, as you can see in my question, I did succeed in making aliases, how can I make them show by default though? – dimus Jan 10 '23 at 14:20
  • @dimus I don't use zfs so this is a guess. Look at [this](https://plantroon.com/changing-disk-identifiers-in-zpool/) and the man page for zpool-import. It looks like you can use something like `zpool-import -d /dev/bay1 -d /dev/bay2 -d... poolname`. – doneal24 Jan 10 '23 at 14:37
  • yes, i did post an answer about doing just that, but it is only a partial answer, I would love to be able to change default names for drives to have a more general solution. – dimus Jan 10 '23 at 14:39
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This is only a partial answer to the question which does work to provide a bay position information for ZFS:

  1. I used parted to change labels for ZFS paritions to something like encl1-3DS where the first part is the bay position and the second is the unique part of the drive's serial.
(parted) p
Model: xxx (scsi)
Disk /dev/sdc: 4001GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:

Number  Start   End     Size    File system  Name       Flags
 1      1049kB  4001GB  4001GB               encl4-28P
 9      4001GB  4001GB  8389kB

  1. zpool export <zpool-name>

  2. zpool import -d /dev/disk/by-partlabel <zpool-name>

  3. Now zpool status -v shows

❯ zpool status -v
  pool: ext
 state: ONLINE
  scan: scrub repaired 0B in 05:42:24 with 0 errors on Fri Jan  6 20:15:57 2023
config:

    NAME           STATE     READ WRITE CKSUM
    ext            ONLINE       0     0     0
      raidz1-0     ONLINE       0     0     0
        encl1-PT8  ONLINE       0     0     0
        encl7-C32  ONLINE       0     0     0
        encl4-28P  ONLINE       0     0     0
        encl2-N75  ONLINE       0     0     0
        encl5-ZT1  ONLINE       0     0     0
        encl6-9RP  ONLINE       0     0     0
        encl8-88F  ONLINE       0     0     0

errors: No known data errors

Not sorted, but it is already much better than /dev/sd*

Still, I would love to have a more general solution that would make a custom alias a default.

dimus
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