Hi!
On 2006-07-18 at 11:30:42, Paul Clements wrote:
> >Personalities : [raid1] [raid6] [raid5] [raid4]
> >md0 : active raid5 hdd3[2] hdb3[0] hda3[1]
> > 585569024 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
> > bitmap: 0/140 pages [0KB], 1024KB chunk
> This indicates that the _in-memory_ bits are all cleared.
Makes sense.
> At array startup, md initializes the in-memory bitmap from the on-disk
> copy. It then uses the in-memory bitmap from that point on, shadowing
> any changes there into the on-disk bitmap.
>
> At the end of a rebuild (which should have happened after you added the
> third disk), the bits should all be cleared. The on-disk bits get
> cleared lazily, though. Is there any chance that they are cleared now?
> If not, it sounds like a bug to me.
I just removed/readded the bitmap as follows, but before that, the 65536
still was there as of 5 minutes ago.
# mdadm /dev/md0 --grow -b none
# for i in hdb3 hdd3 hda3 ; mdadm -X /dev/$i|grep map
Bitmap : 285923 bits (chunks), 3 dirty (0.0%)
Bitmap : 285923 bits (chunks), 3 dirty (0.0%)
Bitmap : 285923 bits (chunks), 65539 dirty (22.9%)
# for i in hdb3 hdd3 hda3 ; mdadm -X /dev/$i|grep map
Bitmap : 285923 bits (chunks), 3 dirty (0.0%)
Bitmap : 285923 bits (chunks), 3 dirty (0.0%)
Bitmap : 285923 bits (chunks), 65539 dirty (22.9%)
(Bitmaps still present, probably I was just too impatient after the
removal)
# mdadm /dev/md0 --grow -b internal
# for i in hdb3 hdd3 hda3 ; mdadm -X /dev/$i|grep map
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
# for i in hdb3 hdd3 hda3 ; mdadm -X /dev/$i|grep map
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4]
md0 : active raid5 hdd3[2] hdb3[0] hda3[1]
585569024 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
bitmap: 140/140 pages [560KB], 1024KB chunk
unused devices: <none>
(Ouch, I hoped there wouldn't be another resync :)
# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4]
md0 : active raid5 hdd3[2] hdb3[0] hda3[1]
585569024 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
bitmap: 1/140 pages [4KB], 1024KB chunk
unused devices: <none>
(Now the in-memory bitmaps seems to be emptied again)
# for i in hdb3 hdd3 hda3 ; mdadm -X /dev/$i|grep map
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
Bitmap : 285923 bits (chunks), 285923 dirty (100.0%)
# for i in hdb3 hdd3 hda3 ; mdadm -X /dev/$i|grep map
Bitmap : 285923 bits (chunks), 0 dirty (0.0%)
Bitmap : 285923 bits (chunks), 0 dirty (0.0%)
Bitmap : 285923 bits (chunks), 0 dirty (0.0%)
And fortunately the on disk ones too...
This discrepancy was there after at least two reboots after the whole
resync has been done. I also did a "scrub" (check) on the array, and
it still did not change.
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