Recovering Data from Remaining RAID 1 Disk

didiw · 01-18-2014, 07:44 AM

Hi,

Quote:

Originally Posted by tkalfaoglu

I have a similar case where RAID1 disks have gone askew.
Unbeknowns to me, /dev/sdb now has NEWER stuff than /dev/sda , because for some months, sda was offline.
Now, sda became online, and sdb is off the raid. How can I recover the contents of sdb?
thanks! -t

I don't know, if your problem is already solved. Just in case you still need help, here is my advice:
Stop the raid, then start the raid with just /dev/sdb and add /dev/sda.

Code:

mdadm --stop <raiddev>
mdadm --assemble ---run -v /dev/mdx /dev/sdb
mdadm --add -v /dev/mdx /dev/sda

This should solve your problem, that you get your newest data back.

Regards
didiw

TekMach · 08-12-2014, 07:58 PM

tommylovell, your advice "Try 'mdadm --assemble --scan'" worked for me to mount the one good disk remaining of a degraded linux raid 1 pair. I know this thread is old but I just had to say thanks! System saw it immediately afterwards as an ext4 partition.

archibaldrazmott · 11-13-2014, 11:29 PM

Quote:

Originally Posted by ljw1004

I used a different technique...
(...)
Conclusion: by stopping MDADM from grabbing ownership of the raid partition, I was able to mount it as its underlying ext3 just fine.

Thanks a lot, ljw1004. Stopping mdadm from using the FS was indeed the solution.
I had to specify the FS type to mount it though,

Code:

mount -t ext4 /dev/sdc3 /mnt/oldstuff -o ro

skris88 · 01-10-2016, 09:43 PM

I'm new on this forum and to Linux so please accept my apologies if I am posting in the wrong thread.

My NAS electronics died (after 7 years).

I was informed (by a unverified web site) that my Thecus NAS uses the XFS file system and that, being RAID1, I should be able to access the data simply off one of the two mirrored drives on my Linux Mint system.

I installed XFS support and tried to mount the drive directly but was unsuccessful. Below is what I just tried...

All assistance will be greatly appreciated.

Thanks,
skris88

Code:

dell-mint ~ # fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000c82a0

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      976895      487424   83  Linux
/dev/sda2          976896    49805311    24414208   83  Linux
/dev/sda3        49807358   976771071   463481857    5  Extended
/dev/sda5        49807360    59570175     4881408   82  Linux swap / Solaris
/dev/sda6        59572224    79101951     9764864   83  Linux
/dev/sda7        79104000    98633727     9764864   83  Linux
/dev/sda8        98635776   976771071   439067648    b  W95 FAT32

WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk doesn't support GPT. Use GNU Parted.


Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1  1953525167   976762583+  ee  GPT
Partition 1 does not start on a physical sector boundary.

Disk /dev/sdc: 640.1 GB, 640135028736 bytes
255 heads, 63 sectors/track, 77825 cylinders, total 1250263728 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00003411

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048  1250263039   625130496    7  HPFS/NTFS/exFAT

Disk /dev/md10: 2047 MB, 2047868928 bytes
2 heads, 4 sectors/track, 499968 cylinders, total 3999744 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Alignment offset: 3072 bytes
Disk identifier: 0x00000000

Disk /dev/md10 doesn't contain a valid partition table

Disk /dev/md0: 998.2 GB, 998155157504 bytes
2 heads, 4 sectors/track, 243690224 cylinders, total 1949521792 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

Disk /dev/md0 doesn't contain a valid partition table

Disk /dev/mapper/vg0-lv0: 948.1 GB, 948114030592 bytes
255 heads, 63 sectors/track, 115268 cylinders, total 1851785216 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/vg0-lv0 doesn't contain a valid partition table

dell-mint ~ # mdadm --assemble --scan
mdadm: /dev/md10 has been started with 1 drive (out of 2).
mdadm: /dev/md0 has been started with 1 drive (out of 2)

dell-mint ~ # mount /dev/md10 /media/nas-hdd
/dev/md10 looks like swapspace - not mounted
mount: you must specify the filesystem type

dell-mint ~ # mount /dev/md0 /media/nas-hdd
mount: unknown filesystem type 'LVM2_member'