RAIDZ2 Expansion didn't increase capacity by expected amount

[hungarianhc]

Hey there, I had RAIDZ2 VDEV, which was 5x8TB SSDs, but showing 7ishTB per disk. Thus, I had 21.4TiB capacity showing in TrueNAS.

That’s expected. I added an identical disk, so my expectation is 28TiB of capacity. However, after adding the drive, it now shows only 25.7TiB.

Where did the rest of the space go? Just to be thorough, I did go into the pool UI and click the “Expand” button, but that didn’t add any additional space.

Thanks in advance for any feedback / help you can provide! I know there have been a handful of VDEV expansion issues posted, but even in the CLI, it doesn’t show more than 25.7TiB.

[LarsR]

Tldr it’s a displaying bug

Edit: For more information see

24.10 RC2 Raidz expansion caused miscalculated available storage

I have a server with 6x18tb (16.37TiB) drives in RAIDz2, and due to hardware limitations, needed to start with 4 drives and expand later. Using 24.10 RC2, I extended my vdev twice, and during the second vdev expansion, I rebooted the system (as zfs documentation said it was safe to reboot during expansion, and I had a need to reboot). After all expansion was completed, it seems like the usable capacity value wasn’t updated to properly reflect the new capacity. [image] I did try the zfs rebal…

[hungarianhc]

Wow. That thread was one giant bag of disappointment.

[winnielinnie]

Disappointment?

How else are you going to shrink large movies files so impressively?