---------- Forwarded message ----------
From: Arman Khalatyan <arm2arm@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@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@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@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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