Hi!
Recently, I've updated one raid1 array to version 1.2 superblocks, in
the (apparently) misguided hope, that it's needed to use bitmaps for
faster resync after failure.
In the process, I've stumbled across a few roadblocks.
First, I've been unable to find out, how to specify the bitmap file
without hardcoding its name in a startup file. Up until now, there was
only a generic "mdadm -As" doing all the work. The other problem, even
if I run this by hand, specifying the bitmap file, the array always
comes up degraded, regardless of any bitmap specified.
Granted, on reboot, some of the times may be because of unclean
shutdowns, other times one of the component is marked as failed (F) in
/proc/mdstat. After a remove/add, and waiting after the resync, all
seems correct, but what irks me, is that mdadm -E always shows some
components as failed even after a completely successful resync.
I *think* that seeing "Array State : uu 1 failed" after the resync
implies that I have to endure the resync after the next reboot.
I remember stopping/starting the array correctly does a resync again,
even without a reboot.
It also seems to me, mdadm does not really store the bitmap file in the
superblock for some reason, and/or there is no way to update this field.
But what I find the most irksome, is that the array
Details follow, sorry for the lengthy dump, I'm not sure if anything is
useless from this.
Kernel is 2.6.16-rc3, mdadm is 2.3.1.
One time when it's started degraded for no apparent reason:
10:21:20 lame kernel: md: md0 stopped.
10:21:20 lame kernel: md: bind<hda3>
10:21:20 lame kernel: md: bind<hdc3>
10:21:20 lame kernel: raid1: raid set md0 active with 1 out of 2 mirrors
Another time, which may result from a somehow unclean shutdown:
10:11:44 lame kernel: md: raid1 personality registered for level 1
10:11:44 lame kernel: md: md driver 0.90.3 MAX_MD_DEVS=256, MD_SB_DISKS=27
10:11:44 lame kernel: md: bitmap version 4.39
10:11:44 lame kernel: md: Skipping autodetection of RAID arrays. (raid=noautodetect)
10:11:44 lame kernel: md: md0 stopped.
10:11:44 lame kernel: md: bind<hda3>
10:11:44 lame kernel: md: bind<hdc3>
10:11:44 lame kernel: md: kicking non-fresh hda3 from array!
10:11:44 lame kernel: md: unbind<hda3>
10:11:44 lame kernel: md: export_rdev(hda3)
16:20:24 lame kernel: md: bind<hda3>
16:20:24 lame kernel: md: syncing RAID array md0
16:20:24 lame kernel: md: minimum _guaranteed_ reconstruction speed: 1000 KB/sec/disc.
16:20:24 lame kernel: md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reconstruction.
16:20:24 lame kernel: md: using 128k window, over a total of 17552232 blocks.
16:58:07 lame kernel: md: md0: sync done.
After the resync, however, the components do not get updated to show
correctness?
------------------------
# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 hda3[2] hdc3[1]
17552232 blocks super 1.2 [2/2] [UU]
unused devices: <none>
------------------------
# mdadm -D /dev/md0; mdadm -E /dev/hd[ac]3
/dev/md0:
Version : 01.02.03
Creation Time : Wed Feb 8 21:24:33 2006
Raid Level : raid1
Array Size : 17552232 (16.74 GiB 17.97 GB)
Device Size : unknown
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Sun Feb 19 17:12:09 2006
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name :
UUID : 4dd4...
Events : 467156
Number Major Minor RaidDevice State
2 3 3 0 active sync /dev/hda3
1 22 3 1 active sync /dev/hdc3
/dev/hda3:
Magic : a92b4efc
Version : 01
Feature Map : 0x0
Array UUID : 4dd4...
Name :
Creation Time : Wed Feb 8 21:24:33 2006
Raid Level : raid1
Raid Devices : 2
Device Size : 35104472 (16.74 GiB 17.97 GB)
Array Size : 35104464 (16.74 GiB 17.97 GB)
Used Size : 35104464 (16.74 GiB 17.97 GB)
Data Offset : 136 sectors
Super Offset : 8 sectors
State : active
Device UUID : aca9...
Update Time : Sun Feb 19 17:12:09 2006
Checksum : dd1ac0a1 - correct
Events : 467156
Array State : uu 1 failed
/dev/hdc3:
Magic : a92b4efc
Version : 01
Feature Map : 0x0
Array UUID : 4dd4...
Name :
Creation Time : Wed Feb 8 21:24:33 2006
Raid Level : raid1
Raid Devices : 2
Device Size : 35104472 (16.74 GiB 17.97 GB)
Array Size : 35104464 (16.74 GiB 17.97 GB)
Used Size : 35104464 (16.74 GiB 17.97 GB)
Data Offset : 136 sectors
Super Offset : 8 sectors
State : active
Device UUID : 66d7...
Update Time : Sun Feb 19 17:12:09 2006
Checksum : d990f459 - correct
Events : 467156
Array State : uU 1 failed
------------------------
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