On 09/06/2013 06:19 AM, NeilBrown wrote:
What I want to do is to completely remove the array so I can mount the
individual partitions anywhere else without the need of mdadm (and
access the data created when the array was running).
If the array uses 0.90 or 1.0 metadata, then having stopped the array you can
simply mount the component devices
If it uses 1.1 or 1.2 you can only access the data via md.
I've mounted filesystems outside of mdadm with version 1.1 and 1.2 metadata. It just requires a little linux jiggery-pokery.
1) Get the data offset using mdadm -E
/dev/sda:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 0f9091ac:202b80dc:31e8820b:f2faeb31
Name : array_3529
Creation Time : Sat Jul 27 20:53:55 2013
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 4194041856 (1999.88 GiB 2147.35 GB)
Array Size : 2097020736 (1999.87 GiB 2147.35 GB)
Used Dev Size : 4194041472 (1999.87 GiB 2147.35 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 7f91df10:05450594:32823f26:924d31ad
Update Time : Mon Sep 2 22:18:19 2013
Checksum : f9f956af - correct
Events : 69985
Device Role : Active device 0
Array State : A. ('A' == active, '.' == missing)
2) Multiply the data offset by 512 to convert sectors to bytes
262144 * 512 = 134217728
3) Setup the disk as a loopback device with the data offset
losetup --offset 134217728 /dev/loop1 /dev/sda
4) Now use the loopback device - it looks just like the md device would.
kpartx -a /dev/loop1
mount -o ro /dev/mapper/loop1p1 /mnt/foo
Of course you have to realize that any modifications you make to the filesystem are not mirrored - you will be forced to resync the mirror if you make any modifications to disk at all.
My $0.02
Tregaron
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