I was attempting to reallocate unused disk space (1.2Tb) from /dev/mapper/centos-home to /dev/centos/root using the steps in How to move disk space from centos-home to centos-root.
After running...
$ umount /dev/mapper/centos-home
$ lvreduce -L 1200G /dev/mapper/centos-home
I'm getting a "can't read superblock" error when i try to remount the drive.
$ mount /dev/mapper/centos-home
mount: /dev/mapper/centos-home: can't read superblock
Before starting, I double-checked to make sure there w enough free (physical space) before running the 'lvreduce' command (there was 2Tb free) - but assume my error was not running a command to first shrink the file system as suggested in LVM logical volume partition corrupted after lvreduce, but also read that this can't be done on XFS systems pr have been unable to locate the specifics.
I tried to recover using,
$ xfs_repair /dev/mapper/centos-home
but the result said
Sorry, could not find valid secondary superblock; Exiting now.
I also tried to restore the size of the LV
$ lvextend -L 1200G /dev/mapper/centos-home
with the result,
New size (307200 extents) matches existing size (307200 extents)
but got the same superblock read error when trying to $ mount the drive.
I'm not sure how deep of a hole I have dug for myself at this point, so here's my question.
What's the best way to recover from this? Or, if I can't recover and mount the damaged drive, do I just delete it and create a new one with the same name? And is this even possible, i.e. do I need to reinstall CentOS? I didn't back up this drive as I haven't been using it. I used the PLESK backup tool so could restore that way, but assume this only works on the /dev/centos/root drive so wouldn't apply here?
I have 4 physical disks set up as RAID5. The other drives and applications are running fine (PLESK lives on /dev/centos/root) and I don't want to damage them.
I'd also like to complete the original task of growing /dev/centos/root.
Here's where things are now....
$ pvscan
PV /dev/sda3 VG centos lvm2 [2.04 TiB / 838.63 GiB free]
Total: 1 [2.04 TiB] / in use: 1 [2.04 TiB] / in no VG: 0 [0 ]
$ vgscan
Reading volume groups from cache.
Found volume group "centos" using metadata type lvm2
$ lvscan
ACTIVE '/dev/centos/swap' [4.00 GiB] inherit
ACTIVE '/dev/centos/home' [1.17 TiB] inherit
ACTIVE '/dev/centos/root' [50.00 GiB] inherit
$ pvdisplay
--- Physical volume ---
PV Name /dev/sda3
VG Name centos
PV Size 2.04 TiB / not usable 0
Allocatable yes
PE Size 4.00 MiB
Total PE 535714
Free PE 214690
Allocated PE 321024
PV UUID qISA9P-0jFe-gk9I-5uuL-OODW-N3af-OkfJlB
$ vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 6
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 2.04 TiB
PE Size 4.00 MiB
Total PE 535714
Alloc PE / Size 321024 / 1.22 TiB
Free PE / Size 214690 / 838.63 GiB
VG UUID zzLRUZ-96Vd-5NGr-YsCl-PJ0l-O8Sy-07Dbqu
$ lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID Dxqf6A-Jtyp-Qdhx-1C0u-CS40-L95c-qF4tRU
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-12-20 09:00:45 -0500
LV Status available
# open 2
LV Size 4.00 GiB
Current LE 1024
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/home
LV Name home
VG Name centos
LV UUID 9QYG2p-0Srl-AluZ-qsBE-wCQ4-BXyN-0hmTp3
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-12-20 09:00:46 -0500
LV Status available
# open 0
LV Size 1.17 TiB
Current LE 307200
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID WrqVSs-EkZI-WD7W-AfsL-2PFX-iZLy-8TPjZr
LV Write Access read/write
LV Creation host, time localhost.localdomain, 2016-12-20 09:01:40 -0500
LV Status available
# open 1
LV Size 50.00 GiB
Current LE 12800
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
