Q: Monitor LVM Shared SAN storage free space via snmpd - thoughts/hints ?

fortechitsolutions

Renowned Member
Jun 4, 2008
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Hi, this is maybe not really a proxmox question, but because of how LVM is used by proxmox from shared storage, the first 'generic' (Cacti:Snmpd) based answers don't seem relevant.

I have just setup a 2-proxmox-node cluster deployment with some large shared FCAL attached disk volumes; which are presented as 2 LVM stores to the proxmox cluster. I typicaly like to use Cacti and snmpd to keep track of long-term history trends on CPU:RAM:NIC use so have just setup this basic monitoring. In a perfect world it would be nice to also be able to easily see what the free:used disk space trends are like as well

so, from CLI for example I see:

Code:
root@proxmox-b:/etc/snmp# lvs
  LV            VG        Attr      LSize   Pool Origin Data%  Move Log Copy%  C
  vm-114-disk-1 lvm-san-1 -wi------ 500.00g
  vm-400-disk-1 lvm-san-1 -wi------ 250.00g
  vm-113-disk-1 lvm-san-2 -wi-ao--- 500.00g
  data          pve       -wi-ao---   3.41t
  root          pve       -wi-ao---  96.00g
  swap          pve       -wi-ao--- 125.00g

root@proxmox-b:/etc/snmp# vgs
  VG        #PV #LV #SN Attr   VSize  VFree
  lvm-san-1   1   2   0 wz--n- 11.93t 11.20t
  lvm-san-2   1   1   0 wz--n- 11.72t 11.23t
  pve         1   3   0 wz--n-  3.64t 16.00g
root@proxmox-b:/etc/snmp# ls -la /dev/lvm-san-1
ls: cannot access /dev/lvm-san-1: No such file or directory

root@proxmox-b:/etc/snmp# ls -la /dev/lvm-san-2/
total 0
drwxr-xr-x  2 root root   60 Jun 18 20:29 .
drwxr-xr-x 17 root root 6560 Jun 18 20:32 ..
lrwxrwxrwx  1 root root    7 Jun 18 20:29 vm-113-disk-1 -> ../dm-4
root@proxmox-b:/etc/snmp#

ie,
-I have got currently 3 different VMs that exist in the cluster which use SAN LVM storage
-only one of these 3 is currently running / accessible from this proxmox-B host
-proxmox-B can see the two LVM storage shared targets (plus his own internal ~3.64 Tb local PVE storage pool that is NOT shared storage)
-and, currently I have only one thing visible under /dev/lvm-san-2 (and nothing exists at /dev/lvm-san-1 - since no volume from there is currently attached to this proxmox-B host).

The suggestion I had from a cacti thread ( http://forums.cacti.net/post-53362.html ) was to monitor disk /dev/myvg/mylv

but that does not seem to be really suitable here.

based on what I do see in current local LVM slice monitors things like /dev/mapper/pve-data (local /var/lib/vz slice) could be monitored just fine -
but the shared LVM does not have a single pointer under /dev/mapper but rather has pointers for each VM which is residing on the shared SAN / for which this Proxmox host has access.

so, I guess I am just wondering if someone else has found a clever solution to this, ie, is it possible to monitor shared SAN LVM disk space via SNMPD/Cacti ?

Thanks!

Tim
 
Last edited:

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