Expanding vdev question

TrueNAS General
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1

Hi,
lately i started using truenas (25.04). So I setup a raidz2 with 1 vdev with 4 drives 20TB (18,1 TiB)
migrated roughly 17TiB of data. AFter that i expanded the vdev with a fith 20TB drive

with the 4 drives i had a capacity of ~ 36,2 TiB
after expanding i got now 43,92 TiB,
While i know that i loose some space due to old parity data but I would have thought my usable space would be at least something like 50+ TiB

I didnt saw any issues after expanding

IS this expected or did I do something wrong?

2

Displayed space is incorrect. Its a bug

The space is available - just displayed wrong

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3

but the shell also prints this

truenas_admin@truenas[~]$ sudo zfs list tank
NAME   USED  AVAIL  REFER  MOUNTPOINT
tank  17.4T  26.5T   151K  /mnt/tank


truenas_admin@truenas[~]$ sudo zpool list tank
NAME   SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
tank  90.9T  35.9T  55.1T        -         -     0%    39%  1.00x    ONLINE  /mnt
4

The zpool list is correct but it reports blocks (inc redundancy) rather than user data.

5x 18.1 TiB = 90.5TiB.

17.4TiB written as 2x data + 2x redundancy = 34.8TiB - which plus metadata will be c. 35.9TiB.

If you rewrite this data then 3x old blocks (6 data, 6 redundancy) will become 2x new blocks (6 data, 4 redundancy) so you will save c. 2/12 and your used data will reduce to c. 30TiB.

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