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

[Karli Sjöberg]

On Thu, 2014-10-23 at 10:11 +0200, Arman Khalatyan wrote:
> 
> ---------- 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.

Did you have separate log devices attached to the pool?

The pool´s name was '16Disks'. Did you have 16 disks in one radiz2 vdev?

/K

> 
> 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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Karli Sjöberg
Swedish University of Agricultural Sciences Box 7079 (Visiting Address
Kronåsvägen 8)
S-750 07 Uppsala, Sweden
Phone:  +46-(0)18-67 15 66
karli.sjoberg at slu.se