LVM shows full volume, but Storage shows plenty of space, backups sometimes timeout

Oct 8, 2020
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Hi

Sorry if everything I'm about to write is not crystal clear: I'm still learning a lot when it comes to server virtualization.

I manage a production server that recently experiences problems when backing up the hosted Windows Server 2016 VMs it hosts.

Yesterday, the whole server froze after a really, really long backup task that took about 10 hours (which make no sense I guess). At some point, the team at OVH detected "a fault on the server", and hard-rebooted it. Obviously, this is unacceptable, as many websites were down for 7 or 10 minutes.

So today, I'm looking at what happened, and I'm thinking: the backup process most probably requires at least some free space on the disk somewhere, so it might got full at some point, which caused the freeze. Please correct me if that makes no sense. :-D

I attached a screenshot showing the only logical volume mounted on the node. It shows it's pretty full. But partitions on that volumes aren't full at all.

I'm also adding the output of vgdisplay and lvdisplay, which I guess may help you help me. ;-)

As I said, I'm still learning at lot. I'm a software developer, not an IT specialist. Thanks a lot for your help!

Code:
vgdisplay
  --- Volume group ---
  VG Name               pve
  System ID             
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               426.59 GiB
  PE Size               4.00 MiB
  Total PE              109208
  Alloc PE / Size       108184 / 422.59 GiB
  Free  PE / Size       1024 / 4.00 GiB
  VG UUID               dPPNiS-FbWJ-aKN0-yzYF-krQm-0Drk-5CBXiq

Code:
lvdisplay
  --- Logical volume ---
  LV Path                /dev/pve/data
  LV Name                data
  VG Name                pve
  LV UUID                leOeEr-YmCq-DzO9-dYdO-4Dtz-xWNr-5Mdbyj
  LV Write Access        read/write
  LV Creation host, time rescue.ovh.net, 2018-06-17 18:39:06 +0000
  LV Status              available
  # open                 1
  LV Size                422.59 GiB
  Current LE             108184
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0
 

Attachments

  • Screenshot_2020-10-08_lvm.png
    Screenshot_2020-10-08_lvm.png
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  • Screenshot_2020-10-08_storage.png
    Screenshot_2020-10-08_storage.png
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Hi,

I guess you use the wrong commands and so you get not the correct values.
Default PVE uses ThinLVM the LVM looks full as the space is reserved for the thinLVM.
use this command and you will see that the data are not full

Code:
lvs /dev/mapper/pve-data
Can you send the output of this command?

Code:
pveversion -v