On Sat, Nov 04, 2017 at 02:09:51AM -0700, L A Walsh wrote:
>
> I just tried blockdev on a HW raid device (/dev/sdb) composed of
> 4K disks that can (w/performance penalty) emulate 512 byte disk
> (i.e. have the 512e feature). It is returning 512.
>
> If the disk is composed of 4K disks, shouldn't the raid show 4K
> as well? Otherwise, how do utils know what alignment to use or
> not to use 512 due to penalty costs? For my formatted disks, I
> use 4K allocation units, so for those, I shouldn't see problems,
> but some other disk subsystems or raw-disk using progs also need to
> know to allocate on 4K boundaries.
>
> Any idea where this info should be showing up?
Try
--getiomin get minimum I/O size
--getioopt get optimal I/O size
or
lsblk --topology
It's possible that RAID (or another stacked device) uses 512
addressing, but for partitioning or mkfs-like tools we care about
minimal and optimal I/O.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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