[ovirt-users] Fwd: Are there some general strategyhow to Iscsi strorage domain?

[Arman Khalatyan]

---------- Forwarded message ----------
From: Arman Khalatyan <arm2arm at gmail.com>
Date: Thu, Oct 23, 2014 at 10:11 AM
Subject: Re: [ovirt-users] Are there some general strategyhow to Iscsi
strorage domain?
To: Trey Dockendorf <treydock at gmail.com>


Thank you Trey for sharing your setup.
I have also one test system with zvol exported with iscsi over 10G.
Unfortunately the difference in performance of zfs over raid controller is
huge, particularly where VM running mysql. I did not try HBAs yet, I have
only LSI/Adaptec/Areca RaidControllers they dont have IT mode. Maybe that
can be the reason.
For sure always one need to find the sweet edge between performance and
reliability.
Just for comparison with yours I get on random IO:
zvol/16Disks/Raid2/tgtd/iscsi/10G-> on VM multiple rsync - ~100-150MB/s,
Same HW but disks with Areca RAID6 -  650MB/s stable even more in some
cases.
The best performance I got on FDR iser->
80% of bare metal performance: 1500MB/s but ovirt goes mad claiming that
Network and Disk devices are saturated. My VM goes time by time to paused
state.
 It is due to that the Ovirt treating all ib devices as 10Gbit cards(in
terms of speed).:(



On Thu, Oct 23, 2014 at 8:30 AM, Trey Dockendorf <treydock at gmail.com> wrote:

> Not sure if it's a solution for you, but ZFS.  My domains are all ZFS
> (using ZFS on Linux in EL6.5) and my backup server receives incremental
> snapshots from primary storage which includes both NFS exports and iSCSI.
> ZFS makes creating block devices for iSCSI very easy, and they are included
> in snapshot replication.  The replication is not HA but disaster recovery
> and off site.
>
> I've hit 300MB/s using ZFS send over IPoIB on my DDR fabric, which isn't
> amazing but not terrible for an old DDR fabric.
>
> ZFS is probably not an easy solution as requires rebuilding your storage,
> but maybe for future use or other readers it will give some useful ideas.
>
> - Trey
> On Oct 22, 2014 11:56 AM, "Arman Khalatyan" <arm2arm at gmail.com> wrote:
>
>> Hi,
>> I have 2x40TB domains each are exported with iser/iscsi with ib and 10Gb
>> interfaces.
>> For sure they are RAID6 storage little bit save on failure.
>> But I was wondered if any way to backup those domains. particularly
>> master one.
>>
>> I was thinking somehow DRBD based replication, with lvm snapshots etc.
>> But it looks like overkill.
>> Will be nice somehow to deploy replicated/HA Master domain with ability
>> to backp on tapes as well.
>>
>> Any ideas are welcome.
>> Thanks,
>> Arman.
>>
>> _______________________________________________
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>>
>>
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