[ovirt-users] Benefits of Cluster separation

[Groten, Ryan]

We only have about 200 VMs, but we’ve run into this bug [1] because we use a high number of direct attach luns on our VMs.  It takes about 5 minutes to scan all the fibre channel luns (same issues exists with iSCSI) and used times out before completing (until we changed the value of vdsTimeout higher).

Also because of the way our FC storage is presented, we have about 1,400 multipath devices presented to each host.  This contributes to really long scan times and I think causes some general slowness in administration side and “Bad Request” 500 Errors when running some storage commands from the API.  VMs themselves still run just fine with no noticeable performance issues though.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1217401



From: Patrick Russell [mailto:patrick_russell at volusion.com]
Sent: Tuesday, August 18, 2015 3:07 PM
To: Matthew Lagoe
Cc: Groten, Ryan; users at ovirt.org
Subject: Re: [ovirt-users] Benefits of Cluster separation

Can I ask at what scale you’re running into issues? We’ve got about 500 VM’s running now in a single cluster.

-Patrick

On Aug 18, 2015, at 4:03 PM, Matthew Lagoe <matthew.lagoe at subrigo.net<mailto:matthew.lagoe at subrigo.net>> wrote:

You can have different cluster policy’s at least, don’t know what other benefits there are however as I haven’t noticed any.

From: users-bounces at ovirt.org<mailto:users-bounces at ovirt.org> [mailto:users-bounces at ovirt.org] On Behalf Of Groten, Ryan
Sent: Tuesday, August 18, 2015 01:59 PM
To: users at ovirt.org<mailto:users at ovirt.org>
Subject: [ovirt-users] Benefits of Cluster separation

We’re running into some performance problems stemming from having too many Hosts/VMs/Disks running from the same Datacenter/Cluster.  Because of that I’m looking into splitting the DC into multiple separate ones with different Hosts/Storage.
But I’m a little confused what the benefit of separating hosts into clusters achieves.  Can someone please explain what the common use cases are?  Since all the clusters in a DC seem to need to see the same storage, I don’t think it would help my situation anyway.

Thanks,
Ryan
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