Pool imported as sdX instead of /dev/disk/by-id

[azeemism]

Hi,

Exporting then importing a pool shows devices listed as sdX under zpool status.

Pool was created as
zpool create spool mirror /dev/disk/by-id/... /dev/disk/by-id/...

Unless the -d options is used each time the pool is imported.
zpool import -d /dev/disk/by-id spool

This is not the case with v0.6.3-766_gfde0d6d.

Not sure if this is somehow related to,
#2482

Using:
VirtualBox
(fresh install) Debian Jessie
(dailies) zfs v0.6.3-222d9d57jessie

Thanks,

Azeem

[azeemism]

I can now report that after the dailies fix,

zfsonlinux/pkg-zfs#138

If a pool is export it is imported back automatically with /dev/disk/by-id after a reboot (tested in VirtualBox). This wasn't the case before the fix.

However if the pool is imported manually, unless the "-d /dev/disk/by-id" option is used it gets imported as /dev/sdX.

---

It would be nice if "zpool import tank" remembered the disk naming format from either,

zpool create tank mirror /dev/disk/by-id /dev/disk/by-id

Or a previous import,

zpool import -d /dev/disk/by-id tank

But that is a minor concern.

[FransUrbo]

However if the pool is imported manually, unless the "-d /dev/disk/by-id" option is used it gets imported as /dev/sdX.

This is most likely due to the zpool.cache file. Try setting 'cachefile=none' on your pool(s) and, if it's still there, remove /etc/zfs/zpool.cache and recreate the initrd.

Also, make sure that USE_DISK_BY_ID='yes' in /etc/default/zfs (before recreating the initrd).=

[azeemism]

Okay will try this out right now.

I assume the command to recreate the initrd is,

mv initrd.img-3.16.0-4-amd64 initrd.img-3.16.0-4-amd64.old
update-initramfs -c -k all

[azeemism]

No change. An exported pool is always imported back as /dev/disk/by-id after reboot.'zpool import spool' is always imported as /dev/sdX

I am assuming it is better to have 'cachefile=none' specified as the default look to be '-', so I guess I should specify this setting moving on for all pool creation.

---

nano /etc/default/zfs
USE_DISK_BY_ID='yes'
Is the default setting which is good.

zpool set cachefile=none spool
Automatically deleted /etc/zfs/zpool.cache
At reboot zpool.cache was recreated

update-initramfs -c -k all

[nicko88]

I think you might be running into this:
http://www.reddit.com/r/zfs/comments/2ugerx/workaround_to_restore_bypath_behavior_for_sata/

[Bronek]

I was experiencing identical issue until I removed zpool import -aN from initramfs ZFS hook of my system. After removing this command, my pools (except for root filesystem) are imported using zpool import -c /etc/zfs/zpool.cache -aN only. Since then the device names in my pools are no longer replaced with /dev/sdX . I raised an issue in ZFS package for my Linux distribution to remove zpool import -aN : archzfs/archzfs#50 .

It is possible that this issue might also be caused by iniramfs script importing indiscriminately all pools at boot time, rather than using zpool.cache

[alexanderhaensch]

I ran into this problem recently.
Wouldn't it be best to default the command
zpool import $pool
to
zpool import -d /dev/by-id $pool

The legacy /dev/sdX is getting more and more unreliable.

[behlendorf]

@alexanderhaensch you can change the default search order with the ZPOOL_IMPORT_PATH environment variable. See zpool.8.

       ZPOOL_IMPORT_PATH
              The  search path for devices or files to use with the pool. This
              is a colon-separated list of directories in  which  zpool  looks
              for  device  nodes and files.  Similar to the -d option in zpool
              import.

That said, you may be right and it's time to change the default. The primary reason it was left as /dev/ for so long was many of the distributions hasn't yet standardized on the /dev/disk/by-id/ convention. However, times are a changing and I can't think of a disro offland that doesn't ship with those udev rules.

It would be great if you set ZPOOL_IMPORT_PATH on your systems to simulate a change in the default search paths.

[alexanderhaensch]

@behlendorf setting the environment variable works great. Now i can import my pool much easier without having the sdX which is changing every boot. :)

[behlendorf]

@alexanderhaensch what did you end up setting it to. The default search order is as follows starting with by-vdev.

char *
zpool_default_import_path[DEFAULT_IMPORT_PATH_SIZE] = {
        "/dev/disk/by-vdev",    /* Custom rules, use first if they exist */
        "/dev/mapper",          /* Use multipath devices before components */
        "/dev/disk/by-uuid",    /* Single unique entry and persistent */
        "/dev/disk/by-id",      /* May be multiple entries and persistent */
        "/dev/disk/by-path",    /* Encodes physical location and persistent */
        "/dev/disk/by-label",   /* Custom persistent labels */
        "/dev"                  /* UNSAFE device names will change */
};

[alexanderhaensch]

For some reason, the function zfs_resolve_shortname does not use vdev to label. On my system always /dev is used.

[alexanderhaensch]

I tested a little bit:
with ZPOOL_IMPORT_PATH="/dev/disk/by-id" :

config:

        NAME                                               STATE     READ WRITE CKSUM
        storage                                            ONLINE       0     0     0
          raidz1-0                                         ONLINE       0     0     0
            ata-ST3000VX000-1CU166_W1F4HC6Q                ONLINE       0     0     0
            ata-ST3000VX000-1CU166_W1F45XDY                ONLINE       0     0     0
            ata-ST3000VX000-1CU166_W1F45WV8                ONLINE       0     0     0

cache
          ata-Corsair_Force_GT_113882030000070000A4-part3  ONLINE       0     0     0 

with ZPOOL_IMPORT_PATH="/dev/disk/by-vdev" :

config:                                                                             
        NAME                                               STATE     READ WRITE CKSUM
        storage                                            ONLINE       0     0     0
          raidz1-0                                         ONLINE       0     0     0
            disk3                                          ONLINE       0     0     0
            disk2                                          ONLINE       0     0     0
            disk1                                          ONLINE       0     0     0
        cache
          ata-Corsair_Force_GT_113882030000070000A4-part3  ONLINE       0     0     0

without any ZPOOL_IMPORT_PATH :

config:
        NAME                                               STATE     READ WRITE CKSUM
        storage                                            ONLINE       0     0     0
          raidz1-0                                         ONLINE       0     0     0
            sdd                                            ONLINE       0     0     0
            sdf                                            ONLINE       0     0     0
            sda                                            ONLINE       0     0     0
        cache
          ata-Corsair_Force_GT_113882030000070000A4-part3  ONLINE       0     0     0

interestingly, the cache is always detected correct with the by-id name. It is the first matching entry. sda,sdd,sdf never match.