This is in a VM, no data at risk.
Two problems:
1. I intentionally removed one of two md raid1 member devices, boot degraded succeeds, clean power off, reconnect the removed md member device, boot succeeds but an automatic resync does not occur for the previously disconnect md members. Maybe this is expected, I'm not sure, but I'd think a better user experience would be autoresync perhaps with a notification?
2. For the raid set with a bitmap, this command succeeds
# mdadm --manage /dev/md126 --re-add /dev/sdb3
However, for the raid set without bitmap (seems the same otherwise, same metadata version), it fails:
# mdadm --manage /dev/md127 --re-add /dev/sdb2
mdadm: --re-add for /dev/sdb2 to /dev/md127 is not possible
# dmesg
[ 3907.162757] md: export_rdev(sdb2)
Configuration details:
-UEFI
- mdadm-3.3-4.fc20.x86_64
- kernel 3.11.10-301.fc20.x86_64
-Two drives (VDI's)
- Idea is to create a resiliently bootable (degraded) system by having duplicate generic EFI System partitions which point to a /boot/grub2/grub.cfg which is on ext4 on md raid1. This part does work, and seems unrelated.
- PARTITIONS
(gdisk, condensed output)
Disk /dev/sda: 167772160 sectors, 80.0 GiB
Number Start (sector) End (sector) Size Code Name
1 2048 411647 200.0 MiB EF00 EFI System
2 411648 1845247 700.0 MiB FD00
3 1845248 165898239 78.2 GiB FD00
Disk /dev/sdb: 167772160 sectors, 80.0 GiB
Number Start (sector) End (sector) Size Code Name
1 2048 411647 200.0 MiB EF00 EFI System
2 411648 1845247 700.0 MiB FD00
3 1845248 165898239 78.2 GiB FD00
- MDSTAT
Personalities : [raid1]
md126 : active raid1 sdb3[1] sda3[0]
81960960 blocks super 1.2 [2/2] [UU]
bitmap: 1/1 pages [4KB], 65536KB chunk
md127 : active raid1 sda2[0]
716224 blocks super 1.2 [2/1] [U_]
- DETAIL
[root@localhost ~]# mdadm -D /dev/md127
/dev/md127:
Version : 1.2
Creation Time : Wed Jul 9 14:41:07 2014
Raid Level : raid1
Array Size : 716224 (699.55 MiB 733.41 MB)
Used Dev Size : 716224 (699.55 MiB 733.41 MB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Update Time : Wed Jul 9 15:31:08 2014
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Name : localhost:boot
UUID : 21743918:8aeb5370:7142e135:aee85500
Events : 41
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
2 0 0 2 removed
- EXAMINE
[root@localhost ~]# mdadm -E /dev/sda2
/dev/sda2:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 21743918:8aeb5370:7142e135:aee85500
Name : localhost:boot
Creation Time : Wed Jul 9 14:41:07 2014
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 1432544 (699.60 MiB 733.46 MB)
Array Size : 716224 (699.55 MiB 733.41 MB)
Used Dev Size : 1432448 (699.55 MiB 733.41 MB)
Data Offset : 1056 sectors
Super Offset : 8 sectors
Unused Space : before=968 sectors, after=96 sectors
State : clean
Device UUID : 7ede7423:80dca499:cf5d3c4d:d0d1493f
Update Time : Wed Jul 9 16:14:38 2014
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 9d336f14 - correct
Events : 43
Device Role : Active device 0
Array State : A. ('A' == active, '.' == missing, 'R' == replacing)
[root@localhost ~]# mdadm -E /dev/sdb2
/dev/sdb2:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 21743918:8aeb5370:7142e135:aee85500
Name : localhost:boot
Creation Time : Wed Jul 9 14:41:07 2014
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 1432544 (699.60 MiB 733.46 MB)
Array Size : 716224 (699.55 MiB 733.41 MB)
Used Dev Size : 1432448 (699.55 MiB 733.41 MB)
Data Offset : 1056 sectors
Super Offset : 8 sectors
Unused Space : before=968 sectors, after=96 sectors
State : clean
Device UUID : a0391710:4c6c3f97:6b3eb23d:779d6e87
Update Time : Wed Jul 9 14:57:13 2014
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : c00df40e - correct
Events : 25
Device Role : Active device 1
Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
- MDADM.CONF
[root@localhost ~]# cat /etc/mdadm.conf
# mdadm.conf written out by anaconda
MAILADDR root
AUTO +imsm +1.x -all
ARRAY /dev/md/boot level=raid1 num-devices=2 UUID=21743918:8aeb5370:7142e135:aee85500
ARRAY /dev/md/pv01 level=raid1 num-devices=2 UUID=1183f7d0:de03bccc:59d6747d:fa2e8a59
Chris Murphy
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