I had a RaidZ2 pool of 4 x 8TB drives and decided to add another 8TB drive using the extend feature. Took a couple of days but didn’t report any errors. Seems like the new numbers don’t add up… I now have Usable Capacity of 17.49TiB Used: 12.46TiB Available: 5.03TiB

added context admin@truenas[~]$ sudo zpool list -v data NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT data 36.4T 25.7T 10.6T - - 0% 70% 1.00x ONLINE /mnt ra…

A TiB is 2^40, whilst a TB is 10^12 which is c. 10% less. So your 8TB drives are c. 7.2TiB, so a 5x 8TB RAIDZ2 will be 5x 7.2TiB = 36TiB in size which is what the zpool list is reporting. Presumably your 4x RAIDZ2 was full-ish - 4x 7.2TiB is 28.8TiB, so alloc. of 25.7TiB seems about right for your …

[image] 24.10 RC2 Raidz expansion caused miscalculated available storage TrueNAS General Seems like a mighty big gotchya with RaidZ expansion. This is the relevant bug report https://ixsystems.atlassian.net/browse/NAS-131728 Basically, the space available is calculated …

That’s disappointing, I probably should have done a bit more research prior to expanding. Just assumed everything was sorted once officially released. So it’s possible that the free space reported by zpool list is accurate and the 5TB discrepancy between that and zfs list is just differences in ca…

Yes -but whilst there is an iX ticket for it, it is actually a limitation / bug of ZFS rather than TrueNAS. I can understand the general difficulties of calculating the actual space used vs. space available in user space terms because of different record sizes for different datasets, snapshots, blo…

appreciate the detailed response, what you said does make sense.

A funny thing happened when extending a pool

TrueNAS General

Stux November 6, 2024, 12:00am 4

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A funny thing happened when extending a pool

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