ZFS Storage Pool Layout

This resource was originally created by user: @Davvo on the TrueNAS Community Forums Archive.

This amazing document, created by iXsystems in February 2022 as a “White Paper”, cleanly explains how to qualify pool performance touching briefly on how ZFS stores data and presents the advantages, performance and disadvantages of each pool layout (striped vdev, mirrored vdev, raidz vdev).
It also presents three common scenarios highlighting their different needs, weaknesses and solutions.

Reading the Introduction to ZFS beforehand is advisable but not required.
Do not assume your drives have 250 IOPS, find your value by reading this resource.

Access the PDF using the orange button.

The previous version contained the following erros, now corrected in the updated resource thanks to @HoneyBadger.

While the resource is valid there are a few mistakes, namely:

  • page 4, Storage space efficiency formula

    • correct: 1/N​
  • page 5, 6x 2-way mirror

    • correct Read IOPS: 3000​

    • correct Write IOPS: 1500​

  • page 6, 4x 3-way mirror

    • correct Streaming read speed: 1200 MB/s​
  • page 11, Scenario 3​

    • a SLOG is not a write cache​

I am in no way affiliated with iXsystems, I just submitted their publicly available White Paper for ease of access.