[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.