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From: Rotate 13 <rabgvzr@gmail.com>
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Subject: [ZFS] Mixed 512 and 4096 byte physical sector size
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Anyone had decent performance running mix of 512 and 4096 ("advanced
format") physical sector size drives on same vdev, with ashift=12 and
correct alignment?  Looking at zmirror, maybe zraid.

>From what I can tell, worst that can happen is I/O amplification and
cache pressure against drive with smaller sector size.  Search shows
people had problems with regular RAID in such configuration; I think
ZFS probably smart enough that only problem is more I/O.  But I am not
ZFS expert, so I ask.

I know it's not ideal, but sometimes must work with what I've got.
And better set ashift=12 from the start on live zpool, as
added/replacement drives in future will probably have 4096 byte
sectors.