Expand boot zfs raid1 with a third disk?

[fips]

Hi,

my proxmox hosts have zfs raid1 with 2 disks as root file system.
Now I got few more disks and want to expand that raid1 with an additional disk.
Or if its unrisky even migrate it to zraid2.

Is that possible or do I have to reinstall proxmox ?

 

[trystan]

Since you have a mirrored vdev, you'd have to add another mirrored vdev (2 disks) to expand the pool and stripe over them all.

 

[LnxBil]

Additional to @trystan's answer:

Now I got few more disks and want to expand that raid1 with an additional disk.

Yes, it is possible to add a third disk to a two disk mirror

Here an example:

root@proxmox:/tmp# dd if=/dev/zero of=zdisk1 bs=1M count=128
root@proxmox:/tmp# dd if=/dev/zero of=zdisk2 bs=1M count=128
root@proxmox:/tmp# dd if=/dev/zero of=zdisk3 bs=1M count=128

root@proxmox:/tmp# zpool create zpooltest mirror /tmp/zdisk1 /tmp/zdisk2

root@proxmox:/tmp# zpool status -v zpooltest
  pool: zpooltest
 state: ONLINE
  scan: none requested
config:

    NAME             STATE     READ WRITE CKSUM
    zpooltest        ONLINE       0     0     0
      mirror-0       ONLINE       0     0     0
        /tmp/zdisk1  ONLINE       0     0     0
        /tmp/zdisk2  ONLINE       0     0     0

errors: No known data errors

root@proxmox:/tmp# zpool attach zpooltest /tmp/zdisk1 /tmp/zdisk3

root@proxmox:/tmp# zpool status zpooltest
  pool: zpooltest
 state: ONLINE
  scan: resilvered 82,5K in 0h0m with 0 errors on Mon Apr  9 18:54:48 2018
config:

    NAME             STATE     READ WRITE CKSUM
    zpooltest        ONLINE       0     0     0
      mirror-0       ONLINE       0     0     0
        /tmp/zdisk1  ONLINE       0     0     0
        /tmp/zdisk2  ONLINE       0     0     0
        /tmp/zdisk3  ONLINE       0     0     0

errors: No known data errors

root@proxmox:/tmp# zpool list zpooltest
NAME        SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
zpooltest   112M   104K   112M         -     0%     0%  1.00x  ONLINE  -

Now you have a three disk mirror with the size of one disk.