[pve-devel] About PVE Backup Integration Guide

[Prashant Patil]

> The block tracking is ideally done via QEMU, then you don't require any special features for the underlying storages.

Yes, we were able to get sector map of disks present on 'Directory' storage type. However, for other storage types such as lvm, lvm-thin, zfs which supports raw disk format, here we could get entire disk as allocated which is not the case in real. I could not find much information on this, hence wanted to know whether this by-design behaviour or we are missing something? Pasting output of qemu-img map below for the 2 GB disk on zfs. Have also tried getting map over ndb but got the same result. Is there anything that we are missing here?

root at be-proxmox1:/dev/pve# qemu-img map -f raw --output=json /dev/zvol/zfs1/vm-105-disk-2
[{ "start": 0, "length": 2147483648, "depth": 0, "present": true, "zero": false, "data": true, "compressed": false, "offset": 0}]


> certain storage types do not support snapshots. In such cases, what is the recommended way to take backup of the running VM?

As mentioned earlier, we have found few storage devices which does not support snapshot, but have found that we can take individual disk snapshot through 'blockdev-snapshot-sync'. If we have to take backup of the VM, then are we supposed to use this command to snapshot all VM disks?

Thanks
Prashant

-----Original Message-----
From: Fiona Ebner <f.ebner at proxmox.com>
Sent: 10 March 2025 02:44 PM
To: Proxmox VE development discussion <pve-devel at lists.proxmox.com>; Thomas Lamprecht <t.lamprecht at proxmox.com>
Cc: Prashant Patil <Prashant.Gamepatil at veritas.com>; Anuradha Joshi <Anuradha.Joshi at veritas.com>; Sudhir Subbarao <Sudhir.Subbarao at veritas.com>; Jason Voneberstein <Jason.vonEberstein at veritas.com>
Subject: Re: [pve-devel] About PVE Backup Integration Guide


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Am 05.03.25 um 07:36 schrieb Prashant Patil via pve-devel:
>   1.  How much part of the plugins method is done?

It is an initial, functional version of the API.

>   2.  How soon we can start the integration?

The patches were not applied yet, feedback is welcome. As Thomas already said "We would be open to fast-track this effort for inclusion with feedback from backup vendors". I'll see if I can get around to post a rebased version this week.

>   3.  Is there any plugin method's documentation already available? If yes, could you please share?

It's part of the patches, see:
https://lore.proxmox.com/pve-devel/20241114150754.374376-10-f.ebner@proxmox.com/

>   1.  How to get allocated blocks/sectors from the snapshot of the raw format virtual disk attached to a running VM (disk present on the block based storage such as lvm, lvm-thin, etc)?
>   2.  How to get allocated blocks/sectors from the snapshot of the vmdk format virtual disk attached to a running VM?
>   3.  As per below link, certain storage types do not support snapshots. In such cases, what is the recommended way to take backup of the running VM?

The block tracking is ideally done via QEMU, then you don't require any special features for the underlying storages. You can also do dirty tracking for incremental backups. See the following for how this is done internally with the proposed API:
https://lore.proxmox.com/pve-devel/20241114150754.374376-4-f.ebner@proxmox.com/
https://lore.proxmox.com/pve-devel/20241114150754.374376-5-f.ebner@proxmox.com/

Best Regards,
Fiona


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