Setting ashift for ZFS (and tuning in general)

[darin755]

So I have a few systems that are built out of cheap hardware. I am looking to try and get as much performance out of them as I can. Right now I am getting around 100mb/s write and 25mb/s read. Each system has different SSDs but fdisk shows 512 byte sector size for all.

Disk /dev/sda: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk model: PNY CS900 500GB
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

My ashift size is currently 12. Should I switch it to 9?

 

[waltar]

You could try ashift=9 but you will not be able to measure a difference and you are on "the better future side" if doing "=12".
When you have nvme with different LBA format support it depends on nvme type but mostly get better results with 4k LBA format when use zfs onto (while with xfs curiously LBA size 512 was better).