[pve-devel] DRBD9 test packages for jessie

[Dietmar Maurer]

> 1- While a VM is running with LVM on top of DRBD, the replicate storages be 
> in secondary mode, ie, only to have a primary storage for each VM that is 
> running (that always was the recommendation of LINBIT for security reasons).

The concept with DRBD9 is a bit different, i.e. we will not use LVM on top 
of DRBD. Instead, DRBD uses LVM internally, and we use 'drbdmanage' to 
configure it. 

The new auto-promote feature make sure the resource is always active 
on only one host.
 
> 2- And when i apply a live migration of a VM, the DRBD plugin first see if 
> the replicated storage is perfectly synchronized (in terms of drbd "oos" 
> that mean: "out of sync"), and if really are perfectly synchronized, the 
> plugin converts the secondary storage in primary for after apply the live 
> migration, and after of a live migration successfully, finally convert the 
> old primary storage in secondary. Of this mode, always we have a primary 
> storage in execution for each VM.

The new architecture will avoid those problem, because we do not
use primary-primary mode.