Re: [Xen-users] Alternatives to a dual-primary DRBD setup

[Daniel Meszaros <meszi@xxxxxxxxxxx>]

Hi!

Sorry for not answering you. I just found your email as a false-positive 
of my SPAM filter. :-(
Am 05/20/2011 09:28 PM, schrieb Bart Coninckx:
> To me it sounds your setup should be fine. It does depends on the nature
> of your guests of course. 10 is not a lot though.
>
> I would try to find the bottleneck:
>
> - do an effective measurement of the DRBD link with netperf
> - investigate none of your guests is swapping heavily consuming a lot of
> I/O
> - investigate your disk performance. RAID5 is not ideal, more striping
> would be better.
>
> I don't think you're very likely to have better performance with other
> setups, like iSCSI.
At the moment I am moving away from Xen as it appears to limit the 
resources I expect to be needed a bit too much, especially Xenserver 
that just reserves up to four VCPUs for dom0.
In the meantime I did a test install of Xenserver 5.6 SP2 and compiled 
and installed the latest version of DRBD on the asynchronous partner of 
the DRBD pair. And it froze already when trying to create the Xenserver 
storage on the DRBD device - in that moment it wasn't yet syncing 
towards the other machine at all.
Now I have Debian Squeeze with KVM running and it runs fine but still 
Standalone-DRBD as I am still migrating my machines over to KVM (mostly 
installing from scratch and migrating the data) ... I am gonna switch 
the other machine to the same setup ... keeping my fingers crossed when 
it's gonna start the DRBD sync again.
Anyway: This is already a lot more than what I got with my Xenserver 5.6 
SP2 attempt, even if I would not have a primary-primary DRBD setup in 
the end.
Another change in the new installation is that I switched over to RAID6 
instead of RAID5 before but I guess this should not make a huge 
difference in means of performance.
I tend to explain the results with a far better support for my 
components due to a newer kernel and less limitations (compared with 
Citrix variant of CentOS in Xenserver).
CU,
Mészi.


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