[DRBD-user] KVM on multiple DRBD resources + IPMI stonith - questions

Phil Stoneman pws at corefiling.com
Fri Jun 24 17:59:51 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 24/06/11 16:45, Noah Mehl wrote:
> I've done a lot of thinking on this point, but I've come to a
> different conclusion.  I think that a drbd resource per guest HD is
> not a great way to go.   I think that adds a lot of complexity and
> overhead you don't necessarily need.

I prefer this route myself. Even though, you're right, there is quite a 
lot more complexity, that's the price you pay for the flexibility. It 
lets you move a single VM from A to B (or even to C if it needs 
dedicated hardware) without having to move lots of them.

> I have not seen a significant performance difference between lvm and
> qcow2. Perhaps you have?

I've not done any testing, and although I wouldn't suspect there's a
massive difference between qcow2 and lvm, I'd personally rather not have
the extra indirection layer of a filesystem at the host level, which is
why I like LVM. Disk is (relatively) cheap these days, and LVM's simple
to grow anyway :)


On Jun 24, 2011, at 10:58 AM, Whit Blauvelt wrote:
>> There also should be a whole lot less needed on the pacemaker-
>> corosync/heartbeat side. What I've been hoping to find is documentation on
>> just enough of pacemaker-corosync/heartbeat to handle this simplified
>> architecture adequately. But most of the documentation isn't aimed towards
>> an architecture like this at all, and just about nothing I've found
>> addresses a KVM environment.

'Just enough' is the approach that proxmox VE seems to take at the 
moment, which is why it's my current favourite :-) It can be made to use 
primary-primary DRBD with LVM volumes, although there's no CLVM - it 
just relies on the proxmox management stuff to not run the same VM on 
both hosts. It's 'good enough' for us though, and is basically a helpful 
wrapper around some simple text config files - the main reason I like it.




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