[DRBD-user] DRBD or not DRBD ?

Dennis Jacobfeuerborn dennisml at conversis.de
Mon Apr 25 17:03:56 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 04/24/2011 10:05 PM, Digimer wrote:
> Comments in-line.
> On 04/24/2011 11:34 AM, Whit Blauvelt wrote:
>> Digimer,
>> All useful stuff. Thanks. I hadn't considered three rather than two
>> networks. That's a good case for it.
>> Here's what I'm trying to scope out, and from your comments it looks to be
>> territory you're well familiar with. I've got two systems set up with KVM
>> VMs, where each VM is on its own LVM, currently each with primary-secondary
>> DRBD, where the primary roles are balanced across the two machines. As far
>> as I can tell, and from past comments here, It's necessary to go
>> primary-primary to enable KVM live migration, which is a very nice feature
>> to have. None of the VMs in this case face critical issues with disk
>> performance, so primary-primary slowing that, if it does in this context,
>> isn't a problem.
> You do need Primary/Primary for live migration.

Why do you need a P/P configuration for live migration? From what I 
understand the VM state will be migrated from the source host to the target 
host and then the storage will be unmounted on the source and mounted again 
on the target. That should make the specific configuration of the storage 
irrelevant as long as it is remotely mountable from both hosts.


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