[illumos-Developer] illumos bug/rfe 453

[wessels]

Hi,

as Garret already pointed out that the best place for the sector size
should be the SD driver. There are a couple of related arc for this:

[1] PSARC/2010/296 Add tunable to control RMW for Flash Devices
http://arc.opensolaris.org/caselog/PSARC/2010/296/mail

[2] PSARC 2008/465 Improved [s]sd-config-list support
http://arc.opensolaris.org/caselog/PSARC/2008/465/mail

[2] PSARC 2008/769 Multiple disk sector size support
http://arc.opensolaris.org/caselog/PSARC/2008/769/mail

Apparently this
(http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6978344)
was integrated just after the code drops stopped. Personaly I think
handling this at the SD driver is a more flexible approach. If a
tunable were provided for zfs than other consumers of SD were still
using an incorrect sector size.
Given that SD will report larger sector sizes than 512 bytes, how will
zfs deal with that? Will it use the reported size when creating the
pool? Can zfs handle different reported sector sizes withing a pool?
Can the data disks be of different sector sizes? Can L2ARC's or slog's
have a different size than the data disks? What happens when larger
sector size devices are later added to the pool?
I need to look into this a bit more but given the age of this thread
and the need for a long term solution I thought it was better to post
some initial thoughts.
Regards,