I have a simple problem with a 2-disk raid-1 configuration that I can’t find the solution for on the internet so I hope someone can help.
One disk failed on my 2-disk raid-1 and I foolishly (physically) removed the disk before software removing it from the array.
The current state is that the array is running degraded with 1 disk. My goal is to add a new disk and return it to a non-degraded 2-disk array.
I still have the failed disk, but I don’t really want to physically re-install it because the last time I tested that, the array started and showed the pre-failed data, not the current data. My theory of this is that the computer switched it’s idea of which disk was /dev/sda and which was /dev/sdb as a result of the original removal. So I’d like to just continue from this state without the confusion of adding that old disk physically back.
Can I just use mdadm -a to add the new disk into this existing array? How do I get rid of the missing ‘ghost’ drive?
Thanks for any help you can provide. I’ll include the output of mdstat and mdadm -D and mdadm.conf below.
—Jim—
$ cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sda1[0]
1953366016 blocks super 1.2 [2/1] [U_]
bitmap: 8/15 pages [32KB], 65536KB chunk
unused devices: <none>
$
$ sudo mdadm -D /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Sat Aug 15 12:52:04 2015
Raid Level : raid1
Array Size : 1953366016 (1862.88 GiB 2000.25 GB)
Used Dev Size : 1953366016 (1862.88 GiB 2000.25 GB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Thu Oct 12 10:36:32 2017
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Name : rockridge:0 (local to host rockridge)
UUID : d22065e7:6796a446:b75d7602:71434594
Events : 560037
Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
2 0 0 2 removed
$
$ cat /etc/mdadm/mdadm.conf
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#
# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
#DEVICE partitions containers
# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes
# automatically tag new arrays as belonging to the local system
HOMEHOST <system>
# instruct the monitoring daemon where to send mail alerts
MAILADDR root
# definitions of existing MD arrays
ARRAY /dev/md/0 metadata=1.2 UUID=d22065e7:6796a446:b75d7602:71434594 name=rockridge:0
# This configuration was auto-generated on Sat, 15 Aug 2015 13:02:22 -0400 by mkconf
$ --
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