Need help to recover root filesystem after a power supply issue

[Andrey Zhunev <a-j@a-j.ru>]

Hello All,

I am struggling to recover my system after a PSU failure, and I was
suggested to ask here for support.

One of the hard drives throws some read errors, and that happen to be
my root drive...
My system is CentOS 7, and the root partition is a part of LVM.

[root@mgmt ~]# lvscan
  ACTIVE            '/dev/centos/root' [<98.83 GiB] inherit
  ACTIVE            '/dev/centos/home' [<638.31 GiB] inherit
  ACTIVE            '/dev/centos/swap' [<7.52 GiB] inherit
[root@mgmt ~]#

[root@tftp ~]# file -s /dev/centos/root
/dev/centos/root: symbolic link to `../dm-3'
[root@tftp ~]# file -s /dev/centos/home
/dev/centos/home: symbolic link to `../dm-4'
[root@tftp ~]# file -s /dev/dm-3
/dev/dm-3: SGI XFS filesystem data (blksz 4096, inosz 256, v2 dirs)
[root@tftp ~]# file -s /dev/dm-4
/dev/dm-4: SGI XFS filesystem data (blksz 4096, inosz 256, v2 dirs)


[root@tftp ~]# xfs_repair /dev/centos/root
Phase 1 - find and verify superblock...
superblock read failed, offset 53057945600, size 131072, ag 2, rval -1

fatal error -- Input/output error
[root@tftp ~]#


smartctl shows some pending sectors on /dev/sda, and no reallocated
sectors (yet?).

Can someone please give me a hand to bring root partition back to life
(ideally)? Or, at least, recover a couple of critical configuration
files...


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Best regards,
 Andrey