[ovirt-users] strange iscsi issue

[Demeter Tibor]

Hi,
Thank you for your reply.
I'm sorry but I don't think so. This storage is fast, because it is a SSD based storage, and I can read/write to it with fast performance.
I know, in virtual environment the I/O always slowest than on physical, but here I have a very large difference. 
Also, I use ext4 FS.

Thanks

Tibor


----- 2015. szept.. 8., 0:40, Alex McWhirter alexmcwhirter at triadic.us írta:

> Unless you're using a caching filesystem like zfs, then you're going to be
> limited by how fast your storage back end can actually right to disk. Unless
> you have a quite large storage back end, 10gbe is probably faster than your
> disks can read and write.
> 
> On Sep 7, 2015 4:26 PM, Demeter Tibor <tdemeter at itsmart.hu> wrote:
>>
>> 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