[PVE-User] Check existing logical volume on iscsi before vm creation

Amin Vakil info at aminvakil.com
Mon Aug 31 16:09:03 CEST 2020

On 8/31/20 6:31 PM, Dominik Csapak wrote:

> this is always a bad idea, because the different installations do not
> communicate and do not know about the others, so
> there is nothing that tells one installation/cluster that some
> disk belongs to another installation.
> do not let multiple clusters access the same storage
> (see also https://pve.proxmox.com/wiki/Storage for that info)
> if that happens and you have vmid collisions, every cluster thinks
> that all disks belong to its own vm (which obviously does not work)
> this is particularly bad for e.g. lvm, since the way we lock
> the storage is based around a cluster so multiple lvm operations
> from multiple cluster will conflict with each other

These are 10 nodes which they are not clustered, I'm creating a cluster
and migrating each vm to cluster in order to prevent vmid collision and

> btw. afaics from your config, this has nothing to do with
> iscsi, but the actual storage is lvm?

Yes, I'm using lvm over iscsi.

> or do you use the iscsi luns directly?
> this should not happen if you have selected the same vgname
> since the second installation should have listed the disks and
> created a new one
> > can you post both storage cfgs from both installations?
> (and tell us which is which?)

All proxmoxs storage configuration are the same as this:
dir: local
	path /var/lib/vz
	content rootdir,iso,snippets,vztmpl,images
	maxfiles 0

nfs: nas02nfs
	export /proxnfs
	path /mnt/pve/nas02nfs
	server a.b.c.d
	content iso,rootdir,backup,vztmpl,images,snippets
	maxfiles 3

iscsi: nas02iscsi
	portal a.b.c.d
	target iqn.2004-04.com.qnap:ts-431x2:iscsi.proxmox.36fa44
	content images

lvm: nas02iscsilvm
	vgname vg_nas02
	content rootdir,images
	shared 1

Ignore the nfs storage, we use it for backups.

> if you used the luns directly, there is no mechanism to
> limit the use of a disk at all, and the admin is responsible
> for handling the assignment
> you can even assign the same lun to multiple vms in the same cluster
> (there are use cases for this, but needs special file systems, e.g.
> ocfs2 or gfs2)
> which is why most users choose to use lvm over iscsi, it
> is then managed (and locked) by our cluster mechanism,
> but only in a single cluster
> Well sorry I didn't state well, but I'm using lvm over iscsi.

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