ZFS Notes

Things not to forget
  • ZFS  can be CPU and Memory intensive.
  • ZFS raidz1, raidz2, etc requires a lot of CPU time. My low power dual core maxes out on 8xraidz2. I upgraded from AMD 270u to AMD X4 960T and my write performance tripled
  • pool = zfs collection of vdevs
  • vdev = collection of disk drive(s), single, n-way mirror, raidz, raidz2, raidz3
  • raidz = similar to raid5
  • Striping happens automatically between vdevs (Use multiple vdevs to increase throughput and I/O)
  • Can not add additional disk(s) to a raidz vdev. But can add addition vdevs to a pool.
  • Can not remove vdevs from pools. Only disks from fault tolerant vdevs (mirror/raidz) can be removed and replaced.
  • Use whole disks, not partitions. Easier that way. (… and faster too?)
  • So far, ZFS is smart enough that if you plug the drives in different SATA ports the pool can still be imported. Example, I moved 2 drives off my motherboard controller to a PCIe addon controller without issue.
  • zpool status
    show the status of all disks in a pool
  • zpool iostat -v 5 [pool name]
    shows I/O’s and bandwidth with a 5 second average on each disk
  • zpool export pool_name / zpool import pool_name
    if needed to move pool to a different machine

Current setup is 2 raidz1 vdevs with 3x3TB drives each. Yielding 12TB

Leave a Reply