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Tools

ZFS Capacity Calculator ZFSBootMenu

RAID Equivalents

  • RAID 0
    • Stripe across disks without parity
    • 100% utilisation
  • RAID 1
    • Mirror
    • 50% utilisation (for 2 way mirror, 1n\frac{1}{n} in general)
  • RAID 5
    • Stripe across disks with parity 1
    • 1−1n1-\frac{1}{n} utilisation (67% for 3 disks, 80% for 5)
  • RAID 6
    • Stripes across disk with parity 2
    • 1−2n1-\frac{2}{n} utilisation (60% for 5 disks)
  • RAID 10
    • Stripe across mirrors
    • 50% utilisation (for 2 way mirror, 1n\frac{1}{n} in general)

Guides

ZFS: You should use mirror vdevs, not RAIDZ.

  • Use mirrored pairs of devs as vdevs instead of RAIDZ
    • Quicker re-silver
    • Very little impact on performance of pool
    • Survival chances
      • 1−(fn−f)1-(\frac{f}{n-f})
      • ff = number of disks already failed
      • nn = number of disks in full pool
      • e.g 8 disk pool (2-way mirrors)
        • 100% survival of the first disk failure
        • 85.7% survival of a second disk failure
        • 66.7% survival of a third disk failure
  • don’t be greedy. 50% storage efficiency is plenty.
  • for a given number of disks, a pool of mirrors will significantly outperform a RAIDZ stripe.
  • a degraded pool of mirrors will severely outperform a degraded RAIDZ stripe. ZFS Handbook ZFS write allocation in 0.7.x
  • Don’t mix rust and SSD in the same pool or vdev Assessing the Potential for Data Loss Expanding ZFS pool on Linux VPS

Install

# debian
sudo apt install zfsutils-linux
# fedora
sudo dnf install https://zfsonlinux.org/epel/zfs-release.el7_9.noarch.rpm
sudo dnf install zfs
sudo modprobe zfs
# arch
sudo yay -S zfs-dkms zfs-utils
sudo modprobe zfs
lsmod | grep zfs

Create

  • Check devices
lsblk
# single disk
sudo zpool create mypool /dev/sdb
# mirror
sudo zpool create mypool mirror /dev/sdb /dev/sdc
# raid-z1
sudo zpool create mypool raidz /dev/sdb /dev/sdc /dev/sdd