[SOLVED] Issue rebuilding ZFS RAID 1 array with new disk

[NessageHostsINC]

Greetings to all,

I have recently encountered a disk (/dev/sdb) failure. I have now replaced the disk, and while the following wiki article https://pve.proxmox.com/wiki/ZFS:_Tips_and_Tricks#Replacing_a_failed_disk_in_the_root_pool, we ran into an issue:

My new disk is slightly smaller than the old one, so when running the following, I have an issue.

sgdisk --replicate=/dev/sdb /dev/sda
Caution! Secondary header was placed beyond the disk's limits! Moving the
header, but other problems may occur!

Warning! Secondary partition table overlaps the last partition by
4688 blocks!
You will need to delete this partition or resize it in another utility.

Problem: partition 3 is too big for the disk.
Aborting write operation!
Aborting write of new partition table.

Spoiler: This is the current ZFS pool status.

zpool status -v
  pool: rpool
 state: DEGRADED
status: One or more devices could not be used because the label is missing or
        invalid.  Sufficient replicas exist for the pool to continue
        functioning in a degraded state.
action: Replace the device using 'zpool replace'.
   see: http://zfsonlinux.org/msg/ZFS-8000-4J
  scan: scrub repaired 0B in 0 days 05:02:09 with 0 errors on Sun Aug 11 05:26:11 2019
config:

        NAME                     STATE     READ WRITE CKSUM
        rpool                    DEGRADED     0     0     0
          mirror-0               DEGRADED     0     0     0
            sda3                 ONLINE       0     0     0
            6945573611984207316  UNAVAIL      0     0     0  was /dev/sdb3

errors: No known data errors

Spoiler: This is the output of lsblk for the two disks.

lsblk /dev/sda
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 931.5G  0 disk
├─sda1   8:1    0  1007K  0 part
├─sda2   8:2    0   512M  0 part
└─sda3   8:3    0   931G  0 part

lsblk /dev/sdb
NAME MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb    8:16   0 931.5G  0 disk

I think we need to shrink the size of sda3 slightly so that we can correctly copy the partition table so that we can safely rebuild the ZFS pool. What would be the safest way of doing this without causing any data loss?

Kindest regards

 

[Stoiko Ivanov]

The partition holding the zfs-pool (sda3 and sdb3 ) need to be the same size (or rather sdb3 needs to be at least as big as sda3).
You can probably shrink the EFI-partition of sdb (i.e. create a smaller sdb2)

I hope this helps!

 

[NessageHostsINC]

Hello,

Thank you very much for getting back to me with such haste.

Do you know whether I can use the same command but specify the size for sdb2 to be 128MB?

sgdisk --replicate=/dev/sdb /dev/sda

Kindest regards

 

[LnxBil]

Do you know whether I can use the same command but specify the size for sdb2 to be 128MB?

No, replicate - as the name suggests - replicates the layout. You have to create a new one.