RAIDZ-1 PBS Mismatched Disk Sizes

pietroaretino

Well-Known Member
Nov 15, 2019
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Please pardon my ignorance but I was under the assumption that you could make a RAIDZ-1 with different sized disks with the caveat that the entire RAID would configure itself around the smallest sized disk. Is this incorrect?
I was setting up a new PBS test server with 3 x 2TB disks and a single 1TB disk, with the idea that once my 4th 2TB disk arrives I would swap it out, at which point the ZFS would resilver and the pool would auto-expand to 6TB usable. I have this configured but during the setup when I attempt to proceed it gives me "mirrored disks must have same size."
Am I wrong that ZFS RAIDZ-1 works with mismatched disks? Thank you.
 
Are you sure you set ip up as RAIDZ? RAIDZ1 is like RAID1 (mirror) while RAIDZ1 is more like HWRAID3. I'm wondering due to the "Mirrored disks must have the same size"

Please post the output of zpool status -v and zpool list -v
 
Thank you for your reply. I cannot give you those outputs as I am unable to create a pool. I am still at the installation phase. I thought RAIDZ used striped-parity, not a mirror?
This is how I am attempting to configure the disks:
photo_2026-04-10_17-26-51.jpg
photo_2026-04-10_17-26-43.jpg
 
You can make this work on the CLI, see man zpool-create:

Code:
The use of differently-sized devices within a single raidz or 
mirror group is also flagged as an error unless -f is specified.
 
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