use zdb to remove pesky device from zfs pool

I had the following problem with a device in my pool:

config:

        NAME                                            STATE     READ WRITE CKSUM
        storage                                         DEGRADED     0     0     0
          mirror-0                                      ONLINE       0     0     0
            WORKING_DISK_1  ONLINE       0     0     0
            WORKING_DISK_2    ONLINE       0   0     0
          mirror-1                                      DEGRADED     0     0     0
            WORKING_DISK_3  ONLINE       0     0     0
            replacing-1                                 DEGRADED     0     0     0
              PROBLEM_DISK  FAULTED      6     1     0  too many errors

However when I tried to replace the drive I got this message:

no such device in pool

I found here that you can use zdb to obtain the GUID of the problem device and replace it that way:

root@nas:~# zdb -l PROBLEM_DISK
failed to unpack label 0
------------------------------------
LABEL 1
------------------------------------
    version: 5000
    name: 'storage'
    state: 0
    txg: 5675107
    pool_guid: 8785893899843624400
    errata: 0
    hostname: 'nas'
    top_guid: 9425730683443378041
    guid: 3449631978925631053
    vdev_children: 2
    vdev_tree:
        type: 'mirror'
        id: 1
        guid: 9425730683443378041
        metaslab_array: 41
        metaslab_shift: 35
        ashift: 12
        asize: 4000782221312
        is_log: 0
        create_txg: 4
        children[0]:
            type: 'disk'
            id: 0
            guid: 17168510556101954329
            path: 'WORKING_DISK_3'
            devid: 'WORKING_DISK_3_ID'
            phys_path: 'pci-0000:00:1f.2-ata-2'
            whole_disk: 1
            DTL: 14700
            create_txg: 4
        children[1]:
            type: 'disk'
            id: 1
    ----->  guid: 3449631978925631053
            path: 'PROBLEM_DISK'
            devid: 'PROBLEM_DISK_ID'
            phys_path: 'pci-0000:00:1f.2-ata-4'
            whole_disk: 1
            DTL: 14699
            create_txg: 4
    features_for_read:
        com.delphix:hole_birth
        com.delphix:embedded_data
    labels = 1 2 3 

I used the guid of the problem disk, and all was well:

zpool replace storage 3449631978925631053 NEW_WORKING_DISK

worked instead of complaining the device I was trying to replace didn’t exist.

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