Re: old raid tools dangerous with 2.6.18?

On Sunday October 1, syrius.ml@no-log.org wrote:

"Richard Bollinger" [off-list ref] writes:

quoted

It appears that raidhotadd doesn't always trigger a resync under 2.6.18.

Starting with a broken raid1 mirror:

Same with evms and 2.6.18. it does not trigger the raid1 resync in any
case. (while it does with 2.6.17)
Have these tools to be updated ?

Well, mdadm-2.x should work, but this is a serious bug in md.

The following patch fixes it and should go in 2.6.18.1.

Thanks and apologies.

NeilBrown


--------------------
Fix problem where hot-added drives are not resynced.

If a drive is added with HOT_ADD_DISK rather than ADD_NEW_DISK,
saved_raid_disk isn't initialised properly, and the drive can be
included in the array without a resync.


### Diffstat output
 ./drivers/md/md.c |    1 +
 1 file changed, 1 insertion(+)

diff .prev/drivers/md/md.c ./drivers/md/md.c

--- .prev/drivers/md/md.c	2006-10-03 17:10:54.000000000 +1000
+++ ./drivers/md/md.c	2006-10-03 17:11:19.000000000 +1000

@@ -3867,6 +3867,7 @@ static int hot_add_disk(mddev_t * mddev,
 	}
 	clear_bit(In_sync, &rdev->flags);
 	rdev->desc_nr = -1;
+	rdev->saved_raid_disk = -1;
 	err = bind_rdev_to_array(rdev, mddev);
 	if (err)
 		goto abort_export;