How can I fix my corrupted RAID1 ext4 partition on a Synology DS212 NAS?
- by Neil
I have two identical 3 TB disks that were in a RAID1 array, where one disk crashed. I replaced the failed disk, but not after the RAID partitions got messed up.
I need to figure out how to restore the RAID array and get at my ext4 partition.
Here are the properties of the surviving disk:
# fdisk -l /dev/sda
fdisk: device has more than 2^32 sectors, can't use all of them
Disk /dev/sda: 2199.0 GB, 2199023255040 bytes
255 heads, 63 sectors/track, 267349 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 267350 2147483647+ ee EFI GPT
# parted /dev/sda print
Model: ATA ST3000DM001-9YN1 (scsi)
Disk /dev/sda: 3001GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number Start End Size File system Name Flags
1 131kB 2550MB 2550MB ext4 raid
2 2550MB 4698MB 2147MB linux-swap(v1) raid
5 4840MB 3001GB 2996GB raid
I replaced the failed drive, and cloned the surviving drive to it so I have something to work with. I cloned the drives with dd if=/dev/sdb of=/dev/sda conv=noerror bs=64M, and now /dev/sda and /dev/sdb are identical.
Here is the RAID information:
# cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md1 : active raid1 sdb2[1]
2097088 blocks [2/1] [_U]
md0 : active raid1 sdb1[1]
2490176 blocks [2/1] [_U]
unused devices: <none>
It seems that md2 is missing.
Here is what testdisk 6.14-WIP finds:
Disk /dev/sda - 3000 GB / 2794 GiB - CHS 364801 255 63
Current partition structure:
Partition Start End Size in sectors
1 P Linux Raid 256 4980735 4980480 [md0]
2 P Linux Raid 4980736 9175039 4194304 [md1]
Invalid RAID superblock
5 P Linux Raid 9453280 5860519007 5851065728
5 P Linux Raid 9453280 5860519007 5851065728
# After a quick search
Disk /dev/sda - 3000 GB / 2794 GiB - CHS 364801 255 63
Partition Start End Size in sectors
D MS Data 256 4980607 4980352 [1.41.12-2197]
D Linux Raid 256 4980735 4980480 [md0]
D Linux Swap 4980736 9174895 4194160
D Linux Raid 4980736 9175039 4194304 [md1]
>P MS Data 9481056 5858437983 5848956928 [1.41.12-2228]
And listing the files on the last partition in the list shows all of my files intact.
What should I do?