On Tuesday February 15, brad@xxxxxxxxxxx wrote:
> G'day all,
>
> I'm not really sure how it's supposed to cope with losing more disks than planned, but filling the
> syslog with nastiness is not very polite.
Thanks for the bug report. There are actually a few problems relating
to resync/recovery when an array (raid 5 or 6) has lost too many
devices.
This patch should fix them.
NeilBrown
------------------------------------------------
Make raid5 and raid6 robust against failure during recovery.
Two problems are fixed here.
1/ if the array is known to require a resync (parity update),
but there are too many failed devices, the resync cannot complete
but will be retried indefinitedly.
2/ if the array has two many failed drives to be usable and a spare is
available, reconstruction will be attempted, but cannot work. This
also is retried indefinitely.
Signed-off-by: Neil Brown <neilb@xxxxxxxxxxxxxxx>
### Diffstat output
./drivers/md/md.c | 12 ++++++------
./drivers/md/raid5.c | 13 +++++++++++++
./drivers/md/raid6main.c | 12 ++++++++++++
3 files changed, 31 insertions(+), 6 deletions(-)
diff ./drivers/md/md.c~current~ ./drivers/md/md.c
--- ./drivers/md/md.c~current~ 2005-02-16 11:25:25.000000000 +1100
+++ ./drivers/md/md.c 2005-02-16 11:25:31.000000000 +1100
@@ -3655,18 +3655,18 @@ void md_check_recovery(mddev_t *mddev)
/* no recovery is running.
* remove any failed drives, then
- * add spares if possible
+ * add spares if possible.
+ * Spare are also removed and re-added, to allow
+ * the personality to fail the re-add.
*/
- ITERATE_RDEV(mddev,rdev,rtmp) {
+ ITERATE_RDEV(mddev,rdev,rtmp)
if (rdev->raid_disk >= 0 &&
- rdev->faulty &&
+ (rdev->faulty || ! rdev->in_sync) &&
atomic_read(&rdev->nr_pending)==0) {
if (mddev->pers->hot_remove_disk(mddev, rdev->raid_disk)==0)
rdev->raid_disk = -1;
}
- if (!rdev->faulty && rdev->raid_disk >= 0 && !rdev->in_sync)
- spares++;
- }
+
if (mddev->degraded) {
ITERATE_RDEV(mddev,rdev,rtmp)
if (rdev->raid_disk < 0
diff ./drivers/md/raid5.c~current~ ./drivers/md/raid5.c
--- ./drivers/md/raid5.c~current~ 2005-02-16 11:25:25.000000000 +1100
+++ ./drivers/md/raid5.c 2005-02-16 11:25:31.000000000 +1100
@@ -1491,6 +1491,15 @@ static int sync_request (mddev_t *mddev,
unplug_slaves(mddev);
return 0;
}
+ /* if there is 1 or more failed drives and we are trying
+ * to resync, then assert that we are finished, because there is
+ * nothing we can do.
+ */
+ if (mddev->degraded >= 1 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+ int rv = (mddev->size << 1) - sector_nr;
+ md_done_sync(mddev, rv, 1);
+ return rv;
+ }
x = sector_nr;
chunk_offset = sector_div(x, sectors_per_chunk);
@@ -1882,6 +1891,10 @@ static int raid5_add_disk(mddev_t *mddev
int disk;
struct disk_info *p;
+ if (mddev->degraded > 1)
+ /* no point adding a device */
+ return 0;
+
/*
* find the disk ...
*/
diff ./drivers/md/raid6main.c~current~ ./drivers/md/raid6main.c
--- ./drivers/md/raid6main.c~current~ 2005-02-16 11:25:25.000000000 +1100
+++ ./drivers/md/raid6main.c 2005-02-16 11:25:31.000000000 +1100
@@ -1650,6 +1650,15 @@ static int sync_request (mddev_t *mddev,
unplug_slaves(mddev);
return 0;
}
+ /* if there are 2 or more failed drives and we are trying
+ * to resync, then assert that we are finished, because there is
+ * nothing we can do.
+ */
+ if (mddev->degraded >= 2 && test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
+ int rv = (mddev->size << 1) - sector_nr;
+ md_done_sync(mddev, rv, 1);
+ return rv;
+ }
x = sector_nr;
chunk_offset = sector_div(x, sectors_per_chunk);
@@ -2048,6 +2057,9 @@ static int raid6_add_disk(mddev_t *mddev
int disk;
struct disk_info *p;
+ if (mddev->degraded > 2)
+ /* no point adding a device */
+ return 0;
/*
* find the disk ...
*/
-
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