Neil, thanks for the insight on 'saved_raid_disk' - this is indeed better.
brassow
==========
Add check to determine if a device needs full resync or if partial resync will do
RAID 5 was assuming that if a device was not In_sync, it must undergo a full
resync. We add a check to see if 'saved_raid_disk' is the same as 'raid_disk'.
If it is, we can safely skip the full resync and rely on the bitmap for
partial recovery instead. This is the legitimate purpose of 'saved_raid_disk',
from md.h:
int saved_raid_disk; /* role that device used to have in the
* array and could again if we did a partial
* resync from the bitmap
*/
Signed-off-by: Jonathan Brassow <jbrassow [at] redhat.com>
Index: linux-2.6/drivers/md/raid5.c
============================================================ =======
--- linux-2.6.orig/drivers/md/raid5.c
+++ linux-2.6/drivers/md/raid5.c
[at] [at] -4858,7 +4858,7 [at] [at] static raid5_conf_t *setup_conf(mddev_t
printk(KERN_INFO "md/raid:%s: device %s operational as raid"
" disk %d\n",
mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
- } else
+ } else if (rdev->saved_raid_disk != raid_disk)
/* Cannot rely on bitmap to complete recovery */
conf->fullsync = 1;
}
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