[StavrosK]

Very nice, thank you, I will try that. I am rather dismayed, however, by learning in this thread that my disks have 4K sector sizes and ZFS autodetected 512 bytes, which means I'll have to destroy the pool and recreate it...

[olgeni]

It happens all the time...

If you run "camcontrol identify ada0" (or whatever your device is) you can find out before it is too late:

sector size logical 512, physical 512, offset 0

This is from a lucky drive of course :)

[StavrosK]

Hmm, there's no such command in Ubuntu, maybe it's from BSD?

[olgeni]

camcontrol is from FreeBSD.

I don't have a Linux box available right now but maybe "hdparm -I" does something similar: "request identification info directly from the drive".

[StavrosK]

Yep, that works:

    Logical  Sector size:                   512 bytes
    Physical Sector size:                  4096 bytes

I'm guessing that's not very nice. My ZFS pool was created with ashift 9 (this is 2^9=512 bytes), when it should be 12 (2^12=4096). I will have to copy everything off and back on again.

For everyone who wants to check, and because I couldn't find info on it, run:

    zdb | grep ashift

And see if it's 9 or 12.