Hi,
On Mon, Jul 03, 2000 at 11:26:49AM -0500, James Bottomley wrote:
> Correct, DPO and FUA bits are forced to zero by sd.c. To have them set
> globally by a flag in the device structure would be easy. To do this on a per
> request structure basis, you'd need an additional flag in the request
> structure. All in all, not a big change. There are wrinkles: the 6 byte
> commands don't support these bits so if you use them the storage better
> support ten (or higher) byte commands.
>
> Could you elaborate more on the problem you're trying to solve here? Using
> cache memory on the drive can be extremely helpful for performance.
Right. Cache memory on the drive is not a problem. Cache memory on a
controller card may be, and in the absence of SCSI reservations, you
need to make sure that the reads are coming from the disk and not the
controller at least for the quorum partition.
If we can safely assert that controller cards just won't cache reads,
then it's a non-issue.
--Stephen
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