I'm trying to get optimal iscsi performance. We're a heavy iscsi shop, with 10g 

I'mm experimenting with SSDs, and the performance in ovirt is way, way less 
than I would have hoped. 
More than an order of magnitude slower.

here's a datapoint.
Im running filebench, with the OLTP workload.
First, i run it on one of the hosts, that has an SSD directly attached.
create an xfs filesystem (created on a vg "device" on top of the SSD), mount it 
with noatime, and run the benchmark.

37166: 74.084: IO Summary: 3746362 ops, 62421.629 ops/s, (31053/31049 r/w), 
123.6mb/s,    161us cpu/op,   1.1ms latency

I then unmount it, and make the exact same device an iscsi target, and create a 
storage domain with it.
I then create a disk for a VM running *on the same host*, and run the benchmark.

The same thing: filebench, oltp workload, xfs filesystem, noatime.

13329: 91.728: IO Summary: 153548 ops, 2520.561 ops/s, (1265/1243 r/w),   
4.9mb/s,    289us cpu/op,  88.4ms latency

62,000 ops/s vs 2500 ops/s.


Someone might be tempted to say, "try making the device directly available, AS 
a device, to the VM".
Unfortunately,this is not an option.
My goal is specifically to put together a new, high performing storage domain, 
that I can use as database devices in VMs.

I'm not expecting the same 62,000 ops/second.
but I was expecting at *least* 5,000. Ideally more like 10,000.

Philip Brown| Sr. Linux System Administrator | Medata, Inc. 
5 Peters Canyon Rd Suite 250 
Irvine CA 92606 
Office 714.918.1310| Fax 714.918.1325 
pbr...@medata.com| www.medata.com
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