ZFS on Alma Linux

ZFS on Alma Linux

Important note

Before you start, keep in mind that the choosen name will also be the mount point from root. So if you call the raidz device “storagebox”, it will be auto-mounted as /storagebox.

Also, for the official ZFS documentation, go to the OpenZFS project website.

Basic installation

First install the requirements

dnf install epel-release kernel-devel
dnf install https://zfsonlinux.org/epel/zfs-release-2-3$(rpm --eval "%{dist}").noarch.rpm
dnf install zfs

Now ensure ZFS gets loaded on boot

echo "zfs" > /etc/modules-load.d/zfs.conf

Create drive

Create a ZFS raidz2 pool (assuming RAID6 alike setup, use raidz1 for RAID5 alike)

zpool create <name> raidz2 <devices>

Now create, if applicable, the LOGs cache (this will be a RAID1 alike mirror)

zpool add <name> log mirror <devices>


See advanced statistics with the zpool status and zpool iostat command

zpool status

# zpool status
  pool: testraid
 state: ONLINE

        NAME        STATE     READ WRITE CKSUM
        testraid    ONLINE       0     0     0
          raidz2-0  ONLINE       0     0     0
            vdb     ONLINE       0     0     0
            vdc     ONLINE       0     0     0
            vdd     ONLINE       0     0     0
            vde     ONLINE       0     0     0
            vdf     ONLINE       0     0     0
          mirror-4  ONLINE       0     0     0
            vdg     ONLINE       0     0     0
            vdh     ONLINE       0     0     0

errors: No known data errors

zpool iostat

# zpool iostat
              capacity     operations     bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
testraid    17.9G  6.60G     63    350  7.88M  50.8M

zpool iostat extended

# zpool iostat -v
              capacity     operations     bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
testraid    18.3G  6.20G     63    350  7.82M  50.9M
  raidz2-0  18.3G  6.20G     63    220  7.82M  23.2M
    vdb         -      -     12     43  1.56M  4.65M
    vdc         -      -     12     44  1.56M  4.65M
    vdd         -      -     12     44  1.56M  4.65M
    vde         -      -     12     44  1.56M  4.65M
    vdf         -      -     12     44  1.56M  4.65M
logs            -      -      -      -      -      -
  mirror-4   146M  1.73G      0    130    519  27.7M
    vdg         -      -      0     65    259  13.8M
    vdh         -      -      0     65    259  13.8M
----------  -----  -----  -----  -----  -----  -----

Drive scrubbing

Use this to auto-scrub the drives once a week

cat << EOF > /etc/cron.d/zfs-check
0 0 1 * * root /usr/sbin/zpool scrub <name>EOF

Replace a faulty disk

After every command, zpool status will show you what it actually did.

Place the faulty device offline

zpool offline <name> /dev/<faulty disk>

Now remove the disk from the system and insert a new one

Now add the disk to the ZFS pool, this can take a lot of time since it will need to resilver the disk into the raidz configuration.

zpool replace <name> /dev/<new disk>

Expand a pool with new disks (or remove a disk)

Please keep in mind that either operation will cause a lot of data shuffling to restore redundancy.

add a disk to an existing pool/vdev

zpool attach <name> <vdev> /dev/<new disk>


See all pool settings

zfs get all <name>

Disable atime so the kernel doesn’t update the access time settings each time

zfs set atime=off <name>

Set extended attributes to go directly with the inodes

zfs set xattr=sa <name>

Set compression to LZ4, its a win!

zfs set compression=lz4 <name>

set your record size to either 64K for databases or 1M for movies

zfs set recordsize=1M <name>


  • When creating a new pool, i’ve found that it sometimes fails with the error “disk or device busy” during the partitioning phase. To resolve this, remove all paritions from the disk, reboot and create a new partition manually. You’ll find that a RAID_MEMBER flag has been set in the GPT or MBR table. Remove this and then remove the created partition.
  • Default ZFS won’t log-cache a-sync writes, causing them to slow down when copying from iSCSI and USB devices. To fix this, run zfs set sync=always <name>.

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