Re: Question about ADMA + RAID5 in the event of disk failure

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On Mon, Jan 4, 2010 at 10:16 AM, Tirumala Reddy Marri <tmarri@xxxxxxxx> wrote:
>
> Hi Dan,
>   I have question about what ADMA + RAID-5 and disk failure. In the event of disk failure what would happen to the descriptors which are queued up the DMA engine for XOR operation ?
> This is what I am trying.
> 1. Create RAID-5 using 4 disks.
> 2. Install xfs file system and mount it.
> 3. Force the disk failure using mdadm -f /dev/md0 /dev/sdc
> 4. Then hot remove the drive mdadm -r /dev/md0 /dev/sdc
> 5. Un-mount the /dev/md0. Then run file system check using xfs_repair -L /dev/md0.
>
>
> I see messages as shown below. These messages doesn't show up if I don't use ADMA. But there seem to be no data loss. But still I there seem to be a some kind of data inconsistency.

Yes, presumably the adma driver as it does not look like parity is
being correctly written to the disks.  Does this driver survive
extended testing with dmatest?  Check that after creating the array
you can run "echo check > /sys/block/md0/md/sync_action" and end up
with zero errors in /sys/block/md0/md/mismatch_cnt.

--
Dan
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