WD Blue SSDs and ashift

MikeyG

Patron
Joined
Dec 8, 2017
Messages
442
I have a bunch of WDS200T2B0A SSDs in a RAIDZ2 pool made of 3 vdevs. The pool was created about 2 years ago with the first 2 vdevs, and those first two vdevs have an ashift of 12 on them (I'm using zdb -U /data/zfs/zpool.cache to find the ashift of the vdevs). The third vdev I added via TrueNAS 12 has an shift of 9.

I'm wondering:

1. Since the pool only has one model of disk, why would the most recent vdev be created differently? All operations were done in the GUI.
2. What should the ashift for these disks be? smartctl reports them as having 512 bytes logical/physical, but I thought all modern SSDs should be configured as 4k with ashift of 12.
3. What are the performance or space implications of having one vdev with a different ashift than the others?
 
Top