[SOLVED] Mount all VM disks on a selected node?

[pc1]

Hello,
Is it possible to mount all created VM disks to copy or backup, or migrate them using only one node? We have Proxmox 7.4 installed over several nodes, a NetApp FibreChannel array with two LVM pools (lvm_NetApp_old_pool_group, lvm_NetApp_new_pool_group), and tens of VMs created there. If I log to some node using ssh, in the /dev folder, sometimes there are both folders visible (/dev/lvm_NetApp_old_pool_group, /dev/lvm_NetApp_old_pool_group), sometimes only one. These folders do not contain links to all VM disks created. Is it possible to repopulate these folders to be able to access all disks created? If I use lvs (or lvs -o +devices), I see all disks listed, so Proxmox knows them all. Or is it some other supported approach to be able to access LVMs from selected nodes?

 

[bbgeek17]

You can only safely activate and access the LVM slices if there are no other hosts accessing these slices. Proxmox cluster reads the the disk context, ie PV and VG on all nodes, it then populates the LV structure/cache. However, the trick to avoid data corruption from multi-host access is to not activate single LV on more than one host.

LVM is not a cluster aware system, PVE is able to use it so with a careful higher level orchestration. If you go behind PVE to activate LVs out of order - you will eventually cause data corruption.

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[pc1]

You are right. I tried one VM to migrate offline to a selected node. Then the /dev/lvm_NetApp_old_pool_group, /dev/lvm_NetApp_new_pool_group were still not populated by its disks, but when I later activated the selected disk of VM-120 there, e.g.

sudo lvchange -a y lvm_NetApp_oldpool_group/vm-120-disk-0


then, the /dev/lvm_NetApp_old_pool_group was populated by a link to the mentioned VM disk and I was able to run fdisk -l on it. Of course, I later manually deactivated it by

sudo lvchange -a n lvm_NetApp_oldpool_group/vm-120-disk-0

to prevent any PVE problems.