snapshot of VM by ignoring iSCSI

tessus

Member
Oct 5, 2020
37
4
13
Toronto, Canada
Is there a way to tell Proxmox to ignore an attached iSCSI disk during a snapshot?

I added a second disk, like so: scsi1: name:0.0.0.scsi-3600120516fb1dc8dbcfbd4334add3ed4,backup=0,cache=writeback,size=4T
Since then I can't take any snapshots anymore. I do understand why that is, but here is an idea or a suggestion for the Proxmox devs:

Is there any way you could add another option for a disk similar to backup=0, e.g. maybe a snapshot=0?
In this case the snapshot would ignore the disk during a snapshot. Is that possible?
 
Is there a way to tell Proxmox to ignore an attached iSCSI disk during a snapshot?

I added a second disk, like so: scsi1: name:0.0.0.scsi-3600120516fb1dc8dbcfbd4334add3ed4,backup=0,cache=writeback,size=4T
Since then I can't take any snapshots anymore. I do understand why that is, but here is an idea or a suggestion for the Proxmox devs:

Is there any way you could add another option for a disk similar to backup=0, e.g. maybe a snapshot=0?
In this case the snapshot would ignore the disk during a snapshot. Is that possible?
AFAICS (not quite sure, would need the complete configuration, e.g. by a "pvereport" so see it) you use the LUN directly as disk for VM. In this case a snapshot is not possible (physical disks cannot be snapshotted, see also overview https://pve.proxmox.com/pve-docs/pve-admin-guide.html#_storage_types). To exclude a disk from snapshots does not really make sense since the idea of snapshots is to keep an exact situation of the entire VM (that's different from backup).

What you can do to get the effect you want to have: detach the disk from the VM, take a snapshot an attach it again.
 
Thanks, Richard. I am aware of that workaround (and as I mentioned I understand and know why the iSCSI disk cannot be included in the snapshot).

Here is a use-case of a snapshot. I create a snapshot, before I do any experiments on that VM or a major update - or if I know I have to rollback to a certain PIT. The data disk on that VM is not important, because it is already on a NAS with Raid-6. (And a backup job of LUNs is done from NAS to NAS).

I don't care about anything on the data disk because I want a snapshot of the OS. I certainly understand that I am "abusing" snapshots this way and that this is not the idea of a snapshot. However, there are always exceptions to the rule. Dealing in absolutes is a mistake.

I asked whether the devs could add another option (exclude disk from snapshot). It can be marked experimental and it can be not supported. What is done under the covers is also the devs choice. e.g. they could force-detach a disk, do the snapshot, and attach the disk again.
It's way more convenient to do a snapshot that takes a second than a backup that runs for several minutes.

Please don't think that I am ignorant. I understand the consequences. This is a usability issue, not a bug. But let's be honest, Proxmox VE is a usability product. Everything that Proxmox does can be done on the command line. People use Proxmox, because it is more convenient and has nice additions out of the box. Adding something that makes people's lives easier is not against the idea of Proxmox, is it?
 
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Thanks, Richard. I am aware of that workaround (and as I mentioned I understand and know why the iSCSI disk cannot be included in the snapshot).

Here is a use-case of a snapshot. I create a snapshot, before I do any experiments on that VM or a major update - or if I know I have to rollback to a certain PIT. The data disk on that VM is not important, because it is already on a NAS with Raid-6. (And a backup job of LUNs is done from NAS to NAS).

I don't care about anything on the data disk because I want a snapshot of the OS. I certainly understand that I am "abusing" snapshots this way and that this is not the idea of a snapshot. However, there are always exceptions to the rule. Dealing in absolutes is a mistake.

I asked whether the devs could add another option (exclude disk from snapshot). It can be marked experimental and it can be not supported. What is done under the covers is also the devs choice. e.g. they could force-detach a disk, do the snapshot, and attach the disk again.
It's way more convenient to do a snapshot that takes a second than a backup that runs for several minutes.

Please don't think that I am ignorant. I understand the consequences. This is a usability issue, not a bug. But let's be honest, Proxmox VE is a usability product. Everything that Proxmox does can be done on the command line. People use Proxmox, because it is more convenient and has nice additions out of the box. Adding something that makes people's lives easier is not against the idea of Proxmox, is it?


A similar request (in this case it was for bind mounts in containers) had been made already a couple of years ago, see https://bugzilla.proxmox.com/show_bug.cgi?id=1007 - feel free to add your point of view there or to open a new case.
 

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