I have the same problem. 3 chunks are always dirty.
I'm using 2.6.38-8-generic and mdadm - v3.1.4 - 31st August 2010
If that's not normal, then maybe what I've done differently is that I
created the array, raid 1, with one live and one missing disk, then
added the second one later after writing a lot of data.
Also, though probably not the cause, I continued writing data while it
was syncing, and a couple times during the syncing, both drives
stopped responding and I had to power off.
# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
[raid4] [raid10]
md127 : active raid1 sdd1[0] sdc1[2]
1904568184 blocks super 1.2 [2/2] [UU]
bitmap: 3/15 pages [12KB], 65536KB chunk
unused devices: <none>
# mdadm -X /dev/sd[dc]1
Filename : /dev/sdc1
Magic : 6d746962
Version : 4
UUID : 43761dc5:4383cf0f:41ef2dab:43e6d74e
Events : 40013
Events Cleared : 40013
State : OK
Chunksize : 64 MB
Daemon : 5s flush period
Write Mode : Allow write behind, max 256
Sync Size : 1904568184 (1816.34 GiB 1950.28 GB)
Bitmap : 29062 bits (chunks), 3 dirty (0.0%)
Filename : /dev/sdd1
Magic : 6d746962
Version : 4
UUID : 43761dc5:4383cf0f:41ef2dab:43e6d74e
Events : 40013
Events Cleared : 40013
State : OK
Chunksize : 64 MB
Daemon : 5s flush period
Write Mode : Allow write behind, max 256
Sync Size : 1904568184 (1816.34 GiB 1950.28 GB)
Bitmap : 29062 bits (chunks), 3 dirty (0.0%)
Quoting NeilBrown <neilb@xxxxxxx>:
> On Thu, October 15, 2009 9:39 am, aristizb@xxxxxxxxxxx wrote:
>> Hello,
>>
>> I have a RAID1 with 2 LVM disks and I am running into a strange
>> situation where having the 2 disks connected to the array the bitmap
>> never clears the dirty chunks.
>
> That shouldn't happen...
> What versions of mdadm and the Linux kernel are you using?
>
> NeilBrown
>
>>
>> I am assuming also that when a RAID1 is in write-through mode, the
>> bitmap indicates that all the data has made it to all the disks if
>> there are no dirty chunks using mdadm --examine-bitmap.
>>
>> The output of cat /proc/mdstat is:
>>
>> md2060 : active raid1 dm-5[1] dm-6[0]
>> 2252736 blocks [2/2] [UU]
>> bitmap: 1/275 pages [12KB], 4KB chunk, file: /tmp/md2060bm
>>
>>
>> The output of mdadm --examine-bitmap /tmp/md2060bm is:
>>
>> Filename : md2060bm
>> Magic : 6d746962
>> Version : 4
>> UUID : ad5fb74c:bb1c654a:087b2595:8a5d04a9
>> Events : 12
>> Events Cleared : 12
>> State : OK
>> Chunksize : 4 KB
>> Daemon : 5s flush period
>> Write Mode : Normal
>> Sync Size : 2252736 (2.15 GiB 2.31 GB)
>> Bitmap : 563184 bits (chunks), 3 dirty (0.0%)
>>
>>
>> Having the array under no IO, I waited 30 minutes but the dirty data
>> never gets clear from the bitmap, so I presume the disks are not in
>> sync; but after I ran a block by block comparison of the two devices I
>> found that they are equal.
>>
>> The superblocks and the external bitmap tell me that all the events
>> are cleared, so I am confused on why the bitmap never goes to 0 dirty
>> chunks.
>>
>> How can I tell if the disks are in sync?
>>
>>
>> Thank you in advance for any help
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