ZFS with three drives

[davidst95]

Hi, I hope this is the correct sub forum to ask this question. I am trying to create a ZFS pool with 3x 2TB drives. I would like to use 2 drives and have the third one as a parity. When I try to create the zpool it just stripes all three drives.

I am using this command:

zpool create -f -m /mnt/zstorage zstorage raidz /dev/nvme1n1p1 /dev/nvme0n1p1 /dev/nvme2n1p1

I also tried ‘raidz1’ and 'raidz2'. When I do a ‘zpool list’ I get this output:

NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT zstorage 5.45T 226K 5.45T - - 0% 0% 1.00x ONLINE -

I assume I would only have about 4tb of usable space since the third one should be parity.

If anyone can tell me what I am doing wrong that would be very helpful. Thank you!

David

 

[Dunuin]

Run zpool status to see how the pool is organized. If you see a "raidz-0" or "raidz1-0" then it is a raidz1. It would be totally normal for zpool list to show 5.45T for a 3x 2TB disk raidz1. The zpool command shows the raw capacity (so data+parity). The zfs command shows the capacity usable for data (so parity already subtracted). So a zpool list should show 6TB and a zfs list should show 4TB.

Also keep in mind that you will probably lose another 1TB because of padding overhead when using zvols and not increasing your volblocksize to atleast 16K. So only 3TB usable for zvols (but 4TB for datasets). And a ZFS pool shouldn`t be filled more than 80%. So right know you shouldn't store more than 2.4TBs of zvols on that pool. Or not more than 3.2TB when using zvols with a 16K volblocksize or any datasets,

To understand padding overhead see here: https://web.archive.org/web/2022050...or-how-i-learned-stop-worrying-and-love-raidz

 

[davidst95]

Thank you so much for the help!

zfs list

is showing 3.5T. I don't think I could have figured that out myself. I amd reading the link you posted now.

David