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I'm attempting to recover (what I'm told is) a btrfs partition from a RAID5 array and I'm a bit stuck on the next step...

The reason I mention it was RAID5 is because the array way deleted in the controller software (!). I was able to recreate without reinitialising and reboot from a recovery CD and I can see all the original partitions:

>fdisk -l

Disk /dev/sda: 7.3 TiB, 8000450330624 bytes, 15625879552 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 65536 bytes / 131072 bytes
Disklabel type: gpt
Disk identifier: 5ED632A8-C1B1-437B-89B5-A05C6312E1C4

Device           Start         End     Sectors  Size Type
/dev/sda1         2048     1026047     1024000  500M EFI System
/dev/sda2      1026048     1288191      262144  128M Microsoft reserved
/dev/sda3      1288192   206088191   204800000 97.7G Microsoft basic data
/dev/sda4  15624953856 15625875455      921600  450M Windows recovery environment
/dev/sda5    206088192 15624953855 15418865664  7.2T Linux filesystem

I thought that was a good sign, unfortunately I'm not able to mount the partition:

mount: /mnt/test: wrong fs type, bad option, bad superblock on /dev/sda5, missing codepage or helper program, or other error.

and a btrfs check says 'no valid Btrfs found on /dev/sda5'.

Is this a lost cause? Just some pointers on the next steps to try would be really appreciated.

16shells
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  • Interesting problem. I have several questions. Do you have access to the other RAID5 devices? "the array way deleted in the controller software" ... Which controller SW? – rickhg12hs Feb 22 '20 at 19:35
  • I can mount and read from the 'EFI' partition (/dev/sda1), but all the other partitions are giving the same problems, although it's not clear what file system they were using (FAT/NTFS, I assume - this is a Dell Precision tower that shipped with Win10 and was rebuilt with Manjaro by an ex-colleague). It was deleted in the RAID controller software on boot up by someone who didn't know what they were doing! I just recreated and booted up hoping it would stil be available... – 16shells Feb 23 '20 at 18:31
  • A RAID5 needs at least 3 devices to make any sense. Where are they? Looking at the RAID deletion instructions in [Dell's Workstation RAID manual](https://downloads.dell.com/manuals/all-products/esuprt_software/esuprt_it_ops_datcentr_mgmt/enterprise-client-solution-resources_white-papers_en-us.pdf), there are multiple RAID controller possibilities but they seem to claim the data is deleted when the RAID is deleted. Depending on how the RAID controller striped the RAID5 data/parity across the devices, it might be easy or impossible to recover data from a single device. – rickhg12hs Feb 23 '20 at 23:13
  • Thanks for the input @rickhg12hs, but the view above is the virtual drive from the recovery os. I've rebuilt the array already from the raid controller s/w and that bits fine - I only mention it as likely reason/background for why the partition/s have become corrupt. – 16shells Feb 24 '20 at 12:27
  • Ahhh, it wasn't clear to me that /dev/sda5 was the **rebuilt** RAID. I wonder if [`TestDisk`](https://www.cgsecurity.org/wiki/TestDisk) can provide any useful analysis or partial recovery. – rickhg12hs Feb 24 '20 at 15:53

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