Windows 2008 R2 - auto tuning level

[jeffhamm]

I have a question about the windows 2008 StarWind Recommended TCP/IP Setting for autotuning:

"netsh int tcp set global autotuninglevel=normal - turns-on TCP auto-tuning"

I have had issues between 2008 and 2003 servers (not involving StarWind or iSCSI), where I had to set the autotuninglevel=disabled on the 2008 server to get the best performance.

How much performance will I lose if I disable the autotuning all together? How does this setting improve StarWind performance?

Thanks,
Jeff

[anton (staff)]

Nobody knows... The answer very much depends on your network hardware (NICs and switches) and network software (NIC drivers, firewall, installed packet monitoring etc). So the only way to know is - run a serie of tests. NTtcp & IPerf to check TCP/IP stack itself and something like I/O Meter and/or SQLIO to test disk subsystem itself. Both BEFORE and AFTER applied network stack settings changes.

I have a question about the windows 2008 StarWind Recommended TCP/IP Setting for autotuning:

"netsh int tcp set global autotuninglevel=normal - turns-on TCP auto-tuning"

I have had issues between 2008 and 2003 servers (not involving StarWind or iSCSI), where I had to set the autotuninglevel=disabled on the 2008 server to get the best performance.

How much performance will I lose if I disable the autotuning all together? How does this setting improve StarWind performance?

Thanks,
Jeff

[oxyi]

When I use iPerf and I specified the TCP Window Size at 128Kbytes, I can get 115MBytes of throughput, but without it I can only get 60MBytes..
so I thought I should disable the autotune and specified in the tcp windows size myself in the registry but I read that Windows just ignore those parameter.

Any other way I can set the TCP Window Size so I can keep that speed and not lose it with the auto-tune function on ?

[anton (staff)]

Unfortunately not the one we're aware of...

When I use iPerf and I specified the TCP Window Size at 128Kbytes, I can get 115MBytes of throughput, but without it I can only get 60MBytes..
so I thought I should disable the autotune and specified in the tcp windows size myself in the registry but I read that Windows just ignore those parameter.

Any other way I can set the TCP Window Size so I can keep that speed and not lose it with the auto-tune function on ?