Usable capacity smaller than usual

TrueNAS General
1

Dear all,

I take care of the NAS of my parents in law. Small machine, not a lot of needs but it works :slight_smile:

Simple RaidZ1 of 2 x 3.64 TB

Today I have been noticed, the Used pool is more than 80%. And it is not because they put suddenly a lot of files, but the usable capacity is now just 2.09 TiB.

So I do not understand why this sudden loss, and if there is a way to get it back to normal.

Welcome to TrueNAS
Last login: Wed Apr 15 18:02:45 CEST 2026 on pts/0
truenas_admin@truenas[~]$ zpool status
pool: VraiNas
state: ONLINE
scan: scrub repaired 0B in 04:51:54 with 0 errors on Wed Apr 1 04:51:57 2026
config:

    NAME                                      STATE     READ WRITE CKSUM
    VraiNas                                   ONLINE       0     0     0
      mirror-0                                ONLINE       0     0     0
        b2741ac1-a39e-4ed4-87f6-ee0bf7ea3927  ONLINE       0     0     0
        5656b700-2158-47b4-8895-11c526371e29  ONLINE       0     0     0

errors: No known data errors

pool: boot-pool
state: ONLINE
scan: scrub repaired 0B in 00:02:52 with 0 errors on Mon Apr 13 03:47:54 2026
config:

    NAME        STATE     READ WRITE CKSUM
    boot-pool   ONLINE       0     0     0
      mirror-0  ONLINE       0     0     0
        sdd3    ONLINE       0     0     0
        sdc3    ONLINE       0     0     0

errors: No known data errors

2

This should be listed as a Mirror of 2 x 3.64 TB and not Raid-Z1. That is a different VDEV setup. I went by your posted pool status to confirm your VDEV setup.

Do you have snapshots? Try working through the following article to check on where or what is using up space. We would need more details or screenshots on the system to try to figure it out.

1 Like
3

Can you post the output of zfs list -o space -r -t all? That will show us exactly what is using up space.

1 Like
4

You are absolutely right, sorry for my mistake.

Actually, by doing that, I found the reason for this mistake: there was a quota on the pool. I do not remember putting it and I do not think my parents in law went up to this screen to edit this specific parameter.

So… I have to stop fixing problems when I am tired, I forgot half of the (bad) things I do :slight_smile:

Thank you for your help anyway, you help me fixing what should be my mistake

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