How to determine which disk failed in a FreeNAS / ZFS setup

Sorry I dont know anything about your hardware but If your OS and device can add the drives on the fly then ZFS will handle the disk additions and filesystem increase no problems. Infact it should be a very pleasing experience :-)

I do not know of any limitations with Mirror compaired to RAIDZ other than the usual mirror vs RAIDz conversations regarding space/redunancy and speed. Which ever you go for just give ZFS the indivdual disks and dont use the RAID , or if your not happy with that then maybe the second best options would be stripe to LUNS in your RAID and let ZFS mirror them ?

Your choice to let ZFS do the redundancy not your Hardware RAID seems to be the accepted method with ZFS if you dont have a mirror or RAIDZ in ZFS then you lose the filesystem self healing abilities that ZFS boasts about.

A old conversation can be found here. Its not the same type of hardware but its the same situation as yours http://web.archiveorange.com/archive/v/LmwutnAQ0OKwhALUNimw

Regards Andy

I haven't used zfs enough to say on data integrity. zpool list gave raidz1-0 ONLINE 0 0 0 c8t1d0p0 ONLINE 0 0 0 c8t2d0p0 ONLINE 0 0 0 c8t3d0p0 ONLINE 0 0 0

smartctl -d sat,12 -a /dev/rdsk/c8t3d0p0 listed specific attributes. -d sat -d ata -d scsi may get it to work depending on what type of drives you have. look at raw read error rate, relocated sector count, seek error rate, hardware ecc, and pending sector relocation. -t short or -t long instead of -a will start a test. the long test can take one or many hours depending on the drive. the read seak and hardware errors are not neccessarly a failure. how ever if they keep jumping between listings they can be a good indicator. Also some drive manufacturers may require you use their tools to get a drive rma'd.

If I were in your position and unsure about the drive I would get a replacement and after either verifying its good through working with the manufacturer or having it rma. I would put in the extra drive as a hot spare so that if it happens again you have another drive ready and waiting. z2 is not a bad idea either but I would still keep a spare in the wings. with the size of drives now they do take a long time to rebuild and it is possible to hit a 2nd error.

as to corrupted files if you still have an original some where else of one of those "corrupted" files do a md5 calculation of it and then see if the corrupted file's md5 matches. that will tell you if bits got damaged. if not then there may be invisible damage to the files. whether its enough damage to be a problem will be up to you.