Hi Denis, Watching closely for the responses to this (haven't used raidz expansion yet, but I was planning to in the near-future -- and besides the "free/used space numbers going astray" issue, this looks like is another potential problem with raidz expansion, and probably even worse for me, since my largest reliable machine -- with ECC RAM -- only has 64GB RAM). A couple of tips: 1) have you searched the Github issues for OpenZFS? ( https://github.com/openzfs/zfs/issues)? if there are any open issues, you can then add a comment mentioning you're also seeing it, and if there's none, you can then open it so the devs will be aware of the issue (many of them don't read this list, at least no assiduously). 2) It would help if you gave us more details, like OS/Distro/Version, machine architecture especially re: storage, output from `zpool status`, if `dmesg` or syslog shows anything, etc. And a couple of questions/comments:
On Mon, Dec 1, 2025 at 8:05 AM Denis Arnst ***@***.***> wrote: Im currently expanding a 4-disk zraid-1 pool on Linux to 5 disks. I however notice extreme spikes in memory doing so. From one second to the other from 64 GB to 128GB (Which is my max ram), which triggers the Linux OOM Killing or freezes the system entirely.
"freezes entirely" meaning "eventually unfreezes itself and continues after X minutes/hours/days" or "freezes entirely" as in "freezes forever and needs a reboot to get the machine back up"? Even with a limited ARC of 24 GB (and just having around 50 GB actually in
use). I reduced now ARC to even 18GB and scaled down some VMs and enabled SWAP on an nvme, which seemed to help a lot.
Good tip on the NVMe SWAP, could be a viable workaround for my case (will just have to buy another, larger NVMe since the one in the machine is currently fully in use). Did someone also experience that? And are there ways around that? Whats
really surprising is the enormous sudden spikes.
Also very interested in hearing from other folks experiencing raidz expansion issues (this or any other). Cheers, -- Durval.
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