[ovirt-users] very very bad iscsi performance

I'm trying to get optimal iscsi performance. We're a heavy iscsi shop, with 10g net. 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. what???? 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 pbrown(a)medata.com| www.medata.com