I have four drives in my PC. When I first started with TrueNAS, I created a simple striped pool using Disk 1. Later, I created a new RAIDZ1 pool with Disks 2, 3, and 4. After the new RAIDZ1 pool was stable, I destroyed the original striped pool and used Storage → rz1_1(new RAIDZ1) → Manage Devices →…

You need to show a bit more data about your pool, but this could be an extreme case of the borked space reporting after raidz expansion.

My raidz1 storage pool appears to be healthy: Topology, Usage, ZFS Health, and Disk Health all show green, and I haven’t seen any warnings.

What about, er… describing your hardware and pool? :roll_eyes: Or sharing the output of /usr/sbin/zpool list -v so we have some numbers to churn? (Please use </> to format.)

Thanks—here’s the command output (after scrubbing the data the reported capacity went up, but it still hasn’t reached the expected size; I’ve got four 16 TB drives, so excluding checksum overhead it should be about 43.65 TB): truenas_admin@cangspirittruenas[~]$ /usr/sbin/zpool list -v NAME …

OK, I think I’ve got a good understanding now—thanks!

TrueNAS RAIDZ1 Expansion Issue – Adding a 4th Disk to a 3-Disk RAIDZ1, Capacity Unchanged

TrueNAS General

etorix July 10, 2025, 6:35pm 7

That’s not much of a discrepancy, and is likely fully explained by this.

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TrueNAS RAIDZ1 Expansion Issue – Adding a 4th Disk to a 3-Disk RAIDZ1, Capacity Unchanged

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