[pve-devel] [PATCH] Add copy_disk and change_disk command

[Dietmar Maurer]

> With this solution, what take in account in the minimal time to recover, 
> as we can start with the copy.
> 
> Perhaps i made some mistakes, but i think that with your solution, it 
> will take time to recover because NAS are less powerfull as Disk Bay (SAN)

Yes, backup is normally not optimized for recovery speed.

> Backup is made like this :
> 
>   * Backup of servers thru Proxmox system on a share (vzdump)
>   * Backup of the share (vzdumps) on a tape
>   * New one wanted : Backup by copying disk from SAN to NAS
> 
> In a 'conventionnal' solution, in case of SAN failure, we have to 
> restore data on NAS (used as SAN but with less power), to gain time on 
> restore, we plan to use copy, and copy should be part of backup.
> That's the reason of my research. We will not bypass 'conventionnal' backup.
> 
> I know that a lvm snapshot is another way to do that. But in this case, 
> it must be between 2 lvm.
> 
> I have seen lvmsync wich permit to make snapshot (from lvm), and 
> transfert only deltas between storages, that could be great, but for 
> now, i don't understand really how to implement this.
> 
> Documentation says :
> 
>   * do a full copy between 2 lvm (on different machines) with dd
>   * configure snapshot on source lvm
>   * and then launch lvmsync to reproduce modifications from source lvm
>     to destination
> 
> 
> a kind of rsync, but without the need of scanning both lvm. Of course, 
> that's the more powerfull. But as far as i know, it needs room on 
> initial disk and i don't know howto estimate it. Furthermore it needs 
> some room (to store snapshot), and disk bay of my client is full.

We will also provide a solution based on zfs:

https://git.proxmox.com/?p=pve-zsync.git;a=summary
 
But this is not yet finished.

> Second : way to do that
> you say :
> 
>     Second, I guess you could add an option to move_disk which avoids
>     changing the config. Changing the config can be done with other
>     API calls (remove/add disk).
> 
> that exactly what i want, but i don't have sufficient experience with 
> perl programming to do that, so it's more easy for me to copy/paste like 
> i do

Looks not really hard to me - maybe you can give it a try. copy/paste large
chunks of code is not really good.