Re: [PATCH 1/1] ipr: Fix for adapter shutdown issue

[James Bottomley <James.Bottomley@SteelEye.com>]

On Wed, 2005-06-15 at 10:34 -0500, Brian King wrote:
> For scsi disks attached to an ipr adapter, the SYNCHRONIZE_CACHE command
> gets sent to the disk and works just like when attached to any other
> HBA. The ipr disk array devices, however, do not support the SYNC_CACHE command,
> nor do they support the caching mode page, so SYNC_CACHE never gets sent.
> So, the shutdown hook is needed to flush the adapter's battery backed write
> cache for all attached disk arrays on system shutdown.

Well, that means you have a whole lot more trouble in 2.6.12 than simply
failing to flush a cache on shutdown.  The barrier code now uses cache
synchronization commands, so if you crash the on-disk image will not be
what a journalling filesystem expects.  As long as the battery keeps the
information alive in the cache, I assume this corrects itself when ipr
next powers up, but if you trusted this, you wouldn't be fussing about
the shutdown cache flush, now would you?

James