[OpenIndiana-discuss] HDD Upgrade problem

[Jim Klimov]

2012-06-11 21:16, michelle wrote:
> Someone posted this comment about my description of the problem on YouTube.
>
> Anyone care to comment please?
>
> nope I don't think it does, I think you experiencing 4K and "Advance
> Format" compatibility issues. The solution is a patched version of
> zpool. I am not so sure that OpenIndiana has been updated to included it.

Well, this is another wording for what I suggested about
older 512 byte-per-sector disks and newer 4KB-per-sector
ones which often emulate and announce 512 bytes-per-sector.
Replacing such older disks with such newer disks is not
a good idea, and while it may be possible, it can lead
to worse performance and heavier corruptions (writing
into a 512B sector requires the disk to read and rewrite
whole 4KB, while breakage of one 4KB native sector breaks
8 emulates 512B sectors).

As for the patched zpool, there are blogs which describe
the issue and publish the updated code and binary. Indeed,
for a number of reasons the fix did not make it into OI
distro, AFAIK. Basically, this part of the issue is that
ZFS trusts what the disk says is its native sector size.
If the disk emulates 512BpS and misleadingly announces
that as the native sector size (which many cheaper drives
apparently do), then ZFS creates pool with an ashift=9
parameter (2^9 = 512), while it should really have used
ashift=12 (2^12 = 4096). For disks which do not lie, it
works properly out of the box. The patched zpool binary
forced ashift=12 at the user's discretion.

HTH,
//Jim Klimov