Kmec wrote:
> Hi,
> I would like to ask for help with some strange behavior of linux
> iscsi. Situation is as follows: iSCSI SAN Dell Equallogic, SAS 10k RPM
> drives, 4x Broadcom NIC or 4x Intel NIC in Dell R900 server (24 cores,
> 64 GB RAM). It's testing environment where we are trying to measure
> SAN Dell EQL performance.
> Totally we are solving 2 different issues:
> 1) In case of running IOmeter test on server running Windows 2008
> server, we are able to get 112 MBps read and 110 MBps write over 1NIC,
> 220 MBps read and 210 MBps over 2 NICs. On SuSE 10 or Centos 66 MBps
> read and 38 MBps write only over one NIC. So I think we can forget
> about finding issues on SAN or switch. Strange is, that with dd or
> hdparm we can get wirespeed. Question is what to do to get same
> numbers from IOmeter on Windows and Linux. We also tried dt tool and
> we get same results as from IOmeter.

What IO sizes are you using? I have seen the windows initiator work well 
with small IO sizes, but the linux initiator perform horribly.

hdparm results should be ok, but dd is sometimes funny when you use the 
default settings.

Could you try disktest (
disktest -PT -T3600 -h1 -K128 -B128k -ID /dev/sdXYZ
disktest -PT -T3600 -h1 -K128 -B128k -ID /dev/sdXYZ -D 0:100

Could you try with the IO sizes that you are giving IO meter. Instread 
of -B128K use whatever you were using with IOmeter.

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