Cannot add disk to VM

[Lucas Rey]

Hello community,
is there any reason because I cannot add a disk to VM due to out of space (while I have enough space on device)?

I created a ZFS pool and it's healthy:

pool: tankone
state: ONLINE
  scan: none requested
config:

        NAME                                          STATE     READ WRITE CKSUM
        tankone                                       ONLINE       0     0     0
          raidz1-0                                    ONLINE       0     0     0
            ata-ST2000VX000-9YW164_S1E0J1RB           ONLINE       0     0     0
            ata-WDC_WD20EFRX-68AX9N0_WD-WCC300741713  ONLINE       0     0     0
            ata-ST2000VX000-9YW164_W1E1SXMB           ONLINE       0     0     0

The mount point shows about 4TB free:

tankone                       3.6T  128K  3.6T   1% /tankone

But, when I try to add a disk to a VM, e.g. 3000 MiB I got:



I tried with 2500 GiB and it works, but Why I cannot add 3000 and more while the Storage shows me 3.52 TiB free ?? :



Thank you very much,
Lucas

 

[dylanw]

Look at the output of zfs list and see how much available space that reports. In the case of raidz1, ZFS uses disk space for parity and other pieces of metadata. With this taken into account, I guess there's not enough remaining space.

 

[apoc]

Check for the blocksize you are using for zvol.
Due to raid-z behaviour you will likely need to modify / move away from the default (8k iirc) to something bigger (32-64k)

Check this recent thread:
https://forum.proxmox.com/threads/zfs-storage-blocks-50-more-space-than-needed.81585/