On 01/27/2016 06:03 AM, NeilBrown wrote:
On Tue, Jan 26 2016, yizhan wrote:
On 10/02/2015 03:55 PM, Neil Brown wrote:
Yi Zhang <yizhan@xxxxxxxxxx> writes:
Hi Neil
When testing 00raid1, found the md127 auto created when use "-B" to build a legacy array without superblocks, is it reasonable?
This happens because udev notices a new device has appeared, looks
inside it, sees that it could be part of an md array, and so runs
"mdadm --incremental" on it.
Hi Neil
I tried the mdadm --incremental, but it doesn't work, below is the
operation.
# mdadm -D /dev/md0
/dev/md0:
Version :
Creation Time : Tue Jan 26 03:16:17 2016
Raid Level : raid1
Array Size : 2097152 (2.00 GiB 2.15 GB)
Used Dev Size : 2097152 (2.00 GiB 2.15 GB)
Raid Devices : 2
Total Devices : 2
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Number Major Minor RaidDevice State
0 7 0 0 active sync /dev/loop0
1 7 1 1 active sync /dev/loop1
# mdadm -D /dev/md127
/dev/md127:
Version : 1.2
Raid Level : raid0
Total Devices : 1
Persistence : Superblock is persistent
State : inactive
Name : 0
UUID : 13ada118:129135ff:686de7b7:4cb71d6d
Events : 17
Number Major Minor RaidDevice
- 9 0 - /dev/md0
# mdadm -I /dev/md127
mdadm: /dev/md127 is not part of an md array.
# mdadm -I /dev/md0
mdadm: cannot reopen /dev/md0: Device or resource busy.
After I stopped md127, the md0 can be used again.
If, after stopping md127, you try
mdadm -I /dev/md0
again it will start /dev/md127 again. This is what udev does which
causes md127 to appear in the first place.
NeilBrown
Thanks Neil
I have tried 'mdadm -I /dev/md0', the /dev/md127 start again
Yi
Thanks
Yi
Sometimes we want udev to do that. Sometimes we don't.
There is no easy way for udev to know what we want.
NeilBrown
pls check below detailed info:
+ mdadm -CR /dev/md0 --level=raid1 -n3 /dev/loop0 /dev/loop1 /dev/loop2
mdadm: /dev/loop0 appears to contain an ext2fs file system
size=58368K mtime=Thu Jan 1 08:00:00 1970
mdadm: Note: this array has metadata at the start and
may not be suitable as a boot device. If you plan to
store '/boot' on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
--metadata=0.90
mdadm: /dev/loop1 appears to contain an ext2fs file system
size=38912K mtime=Thu Jan 1 08:00:00 1970
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
+ mdadm --wait /dev/md0
+ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [raid1]
md0 : active raid1 loop2[2] loop1[1] loop0[0]
19968 blocks super 1.2 [3/3] [UUU]
unused devices: <none>
+ mdadm -S /dev/md0
mdadm: stopped /dev/md0
+ mdadm -B /dev/md0 -l raid1 -n2 /dev/loop0 /dev/loop1
mdadm: array /dev/md0 built and started.
+ sleep 2
+ cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [raid1]
md127 : inactive md0[0](S)
19968 blocks super 1.2
md0 : active raid1 loop1[1] loop0[0]
20000 blocks super non-persistent [2/2] [UU]
unused devices: <none>
[root@dhcp-12-171 bug]# uname -r
4.2.0
[root@dhcp-12-171 bug]# mdadm -D /dev/md0
/dev/md0:
Version :
Creation Time : Mon Sep 7 20:21:20 2015
Raid Level : raid1
Array Size : 20000 (19.53 MiB 20.48 MB)
Used Dev Size : 20000 (19.53 MiB 20.48 MB)
Raid Devices : 2
Total Devices : 2
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Number Major Minor RaidDevice State
0 7 0 0 active sync /dev/loop0
1 7 1 1 active sync /dev/loop1
[root@dhcp-12-171 bug]# mdadm -D /dev/md127
/dev/md127:
Version : 1.2
Raid Level : raid0
Total Devices : 1
Persistence : Superblock is persistent
State : inactive
Name : dhcp-12-171.nay.redhat.com:0 (local to host dhcp-12-171.nay.redhat.com)
UUID : 40ace956:a9dd0793:f4984d2b:8431b92b
Events : 17
Number Major Minor RaidDevice
- 9 0 - /dev/md0
Best Regards,
Yi Zhang
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