On Mon, 10 Jun 2013 10:15:05 -0400 Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
wrote:
> A few outstanding questions that I have, maybe Neil or someone more
> familiar with the code could answer.
>
> Q1 - Is mddev->chunk_sectors is always zero for RAID1?
Not always. But often. It is largely ignored. I think the only effect is
to round the size of the device down to a multiple of the chunk size.
>
> Q2 - I noticed handle_write_finished calls narrow_write_error to try and
> potentially avoid failing an entire device. In my tests,
> narrow_write_error never succeeded as rdev->badblocks.shift = -1.
Yes. You would need a newer mdadm (from my git tree) to get badblocks.shift
to something else.
>
> I think this part of the bad block list code Neil has been working
> on. I don't suppose this is the proper place for MD to reset
> write_same_max_bytes to disable future WRITE SAME and handling the
> individual writes here instead of the block layer?
If a drive reports that WRITE SAME works, but it doesn't, then I'm not sure
that I can be happy about working with that drive.
If a drive has some quirky behaviour wrt WRITE SAME, then that should be
handled in some place where 'quirks' are handled - certainly not in md.
I've applied that patch below - thanks.
NeilBrown
>
> Regards,
>
> -- Joe
>
>
> From b12c24ee0fce802f35263da65d236694b01c99cf Mon Sep 17 00:00:00 2001
> From: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
> Date: Fri, 7 Jun 2013 15:25:54 -0400
> Subject: [PATCH] raid1: properly set blk_queue_max_write_same_sectors
>
> MD RAID1 chunk_sectors will always be zero, unlike RAID0, so RAID1 does
> not need to worry about limiting the write same sectors in that regard.
> Let disk_stack_limits choose the minimum of the RAID1 components write
> same values.
>
> Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx>
> ---
> drivers/md/raid1.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index fd86b37..3dc9ad6 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -2821,9 +2821,6 @@ static int run(struct mddev *mddev)
> if (IS_ERR(conf))
> return PTR_ERR(conf);
>
> - if (mddev->queue)
> - blk_queue_max_write_same_sectors(mddev->queue,
> - mddev->chunk_sectors);
> rdev_for_each(rdev, mddev) {
> if (!mddev->gendisk)
> continue;
Attachment:
signature.asc
Description: PGP signature
