HELP NEEDED - Can't mount RAID volume after changing failed boot drive

iannbrown · 02-17-2019, 02:54 AM

Hi

I am a Linux newbie. I'm trying to help a friend who's boot disk died on a Fedora installation which is used as a Plex server.

I've replaced the main drive and re-installed Fedora fine.
I've re-inserted the 2 RAID1 disks and they are detected, and then after much reading used mdadm to scan and assemble the disks so the RAID volume shows in disks, however it won't display and gives the following error

Unable to Access Location
Error mounting /dev/md0p1 at run/media/plex/_mnt_md0: cannot
mount; probably corrupted filesystem on dev/md0p1

The RAID volume is 2 x 3Tb drives which contains all their Plex media,so I am desparate to access it.

I need to either:

Be able to fix the array so it is readable

or

Simply be able to read one of the disks so that I can copy the data off to another drive.

Any suggestions welcomed. Thanks

syg00 · 02-17-2019, 03:05 AM

Let's see this - use [code] tags (Advanced button, then "#").

Code:

lsblk -f

iannbrown · 02-17-2019, 03:57 AM

Thanks syg00 for the help.

Code:

[plex@plexbox-localdomain ~]$ lsblk -f
NAME FSTYPE LABEL              UUID                                   MOUNTPOINT
sda                                                                   
├─sda1
│    ext4                      815ac1df-32a2-4fa0-8f83-efd78a74e080   /boot
└─sda2
     LVM2_m                    p0c6TD-gs93-IJwh-tF7r-PLa9-heKX-1x0izS 
  ├─fedora-root
  │  ext4                      d9f4e14b-c109-4874-b409-6a76dbd7e2b8   /
  ├─fedora-swap
  │  swap                      f714f7a2-0304-44ea-b49d-44528d393264   [SWAP]
  └─fedora-home
     ext4                      f7e6eed9-c9c5-48c4-abab-10920020a298   /home
sdb  linux_ localhost.localdomain:0
│                              a1fd7767-cf9d-1516-46cc-ab84258d3507   
└─md0
                                                                      
  └─md0p1
     xfs    /mnt/md0           83c6e4bf-cfcf-4856-a91f-2cc38e01d06e   
sdc  linux_ localhost.localdomain:0
│                              a1fd7767-cf9d-1516-46cc-ab84258d3507   
└─md0
                                                                      
  └─md0p1
     xfs    /mnt/md0           83c6e4bf-cfcf-4856-a91f-2cc38e01d06e

/sdb and /sdc are the two raid disks

syg00 · 02-17-2019, 04:01 AM

Ugh - edit that, and change the [quote] tags to [code]. That way we might be able to read it.

iannbrown · 02-17-2019, 04:39 AM

syg00 · 02-17-2019, 05:15 AM

Much better ....

How about

Code:

cat /proc/mdstat

iannbrown · 02-17-2019, 05:17 AM

Code:

plex@plexbox-localdomain ~]$ cat /proc/mdstat
Personalities : [raid1] 
md0 : active raid1 sdb[1] sdc[0]
      2930135488 blocks super 1.2 [2/2] [UU]
      bitmap: 0/22 pages [0KB], 65536KB chunk

unused devices: <none>

syg00 · 02-17-2019, 05:47 AM

That all looks ok, what nodes have been created ?.

Code:

ls /dev/md*

iannbrown · 02-17-2019, 05:07 PM

Code:

[plex@plexbox-localdomain ~]$ ls /dev/md*
/dev/md0  /dev/md0p1

/dev/md:
localhost.localdomain:0  localhost.localdomain:0p1

syg00 · 02-18-2019, 05:35 AM

I would try something like the following to mount what appears t be the reconstructed RAID.

Code:

sudo mkdir /mnt/tempry
sudo mount /dev/md0p1 /mnt/tempry
df -hT

iannbrown · 02-19-2019, 02:10 AM

Thanks for continuing to help.

This failed after step 2, see below

Code:

[plex@plexbox-localdomain ~]$ sudo mkdir /mnt/tempry
[sudo] password for plex: 
[plex@plexbox-localdomain ~]$ sudo mount /dev/md0p1 /mnt/tempry
mount: /mnt/tempry: cannot mount; probably corrupted filesystem on /dev/md0p1.

This is the same general error I get when mounting through the Disks utility.

Also, I'm happy to give you TeamViewer access to this machine if you would like, maybe it would be quicker and less tedious for you?

thanks again

Peverel · 02-20-2019, 01:55 PM

If you run:

fsck -n /dev/md0p1

you should get an error list without risking damage to the files: if you left out the -n then it would try to correct them. No guarantees, though.

iannbrown · 02-20-2019, 05:02 PM

Code:

[plex@plexbox-localdomain ~]$ sudo fsck -n /dev/md0p1
[sudo] password for plex: 
fsck from util-linux 2.32.1
If you wish to check the consistency of an XFS filesystem or
repair a damaged filesystem, see xfs_repair(8).

so then...

Code:

[plex@plexbox-localdomain ~]$ sudo xfs_repair -n /dev/md0p1
Phase 1 - find and verify superblock...
Phase 2 - using internal log
        - zero log...
ALERT: The filesystem has valuable metadata changes in a log which is being
ignored because the -n option was used.  Expect spurious inconsistencies
which may be resolved by first mounting the filesystem to replay the log.
        - scan filesystem freespace and inode maps...
sb_fdblocks 266982522, counted 266990714
        - found root inode chunk
Phase 3 - for each AG...
        - scan (but don't clear) agi unlinked lists...
        - process known inodes and perform inode discovery...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - process newly discovered inodes...
Phase 4 - check for duplicate blocks...
        - setting up duplicate extent list...
        - check for inodes claiming duplicate blocks...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
No modify flag set, skipping phase 5
Phase 6 - check inode connectivity...
        - traversing filesystem ...
        - traversal finished ...
        - moving disconnected inodes to lost+found ...
Phase 7 - verify link counts...
No modify flag set, skipping filesystem flush and exiting.

syg00 · 02-20-2019, 10:15 PM

So when the original system died it broke the XFS filesystem. See the manpage for xfs_repair; notably the "-L" option.
Read the warnings, and the section "Dirty Logs" at the end. Your (friends) call, but essentially you probably have no option. Even if you lose some files, not the end of the world I guess.