[bug?] raid1 integrity checking is broken on 2.6.18-rc4
From: Chuck Ebbert
Date: Sat Aug 12 2006 - 02:51:49 EST
Doing this on a raid1 array:
echo "check" >/sys/block/md0/md/sync_action
Activity lights on both mirrors show activity for a while,
then the array status prints on the console.
On 2.6.18-rc4 + the below patch:
Drive activity light blinks once on one drive, then the
array status prints (obviously no checking takes place.)
Applied hotfix on 2.6.18-rc4:
--- .prev/drivers/md/md.c 2006-08-08 09:00:44.000000000 +1000
+++ ./drivers/md/md.c 2006-08-08 09:04:04.000000000 +1000
@@ -1597,6 +1597,19 @@ void md_update_sb(mddev_t * mddev)
+ if (mddev->degraded && mddev->sb_dirty == 3)
+ /* If the array is degraded, then skipping spares is both
+ * dangerous and fairly pointless.
+ * Dangerous because a device that was removed from the array
+ * might have a event_count that still looks up-to-date,
+ * so it can be re-added without a resync.
+ * Pointless because if there are any spares to skip,
+ * then a recovery will happen and soon that array won't
+ * be degraded any more and the spare can go back to sleep then.
+ mddev->sb_dirty = 1;
sync_req = mddev->in_sync;
mddev->utime = get_seconds();
if (mddev->sb_dirty == 3)
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