[ovirt-users] strange iscsi issue

[Demeter Tibor]

Hi All, 

I have to create a test environment for testing purposes, because we need to testing our new 10gbe infrastructure. 
One server that have a 10gbe nic - this is the vdsm host and ovirt portal. 
One server that have a 10gbe nic - this is the storage. 

Its connected to each other throught a dlink 10gbe switch. 

Everything good and nice, the server can connect to storage, I can make and run VMs, but the storage performance from inside VM seems to be 1Gb/sec only. 
I did try the iperf command for testing connections beetwen servers, and it was 9.40 GB/sec. I have try to use hdparm -tT /dev/mapper/iscsidevice and also it was 400-450 MB/sec. I've got same result on storage server. 

So: 

- hdparm test on local storage ~ 400 mb/sec 
- hdparm test on ovirt node server through attached iscsi device ~ 400 Mb/sec 
- hdparm test from inside vm on local virtual disk - 93-102 Mb /sec 

The question is : Why? 

ps. I Have only one ovirtmgmt device, so there are no other networks. The router is only 1gbe/sec, but i've tested and the traffic does not going through this. 

Thanks in advance, 

Regards, 
Tibor 



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