optimizing ftp perfomrance by tunning kernel parameters on hpux 11 ?

[Henrique Silva_3]

After some app data flow study, one of the issues found was that during a file attachment operation at the client level,that uses ftp as it underlying transport mechanism from client to server, we could see that the frames or packets where not optmized for greater throughput.

when playing with the tcp window size on a windoze box, changing from 17 K ( default ) to 64k, we could see that the improvement was 100% better performance on some cases, since the packets were now being filled up instead of half empty.

now, we are trying to identify what are the kernel parameters on the unix box, which is where the ftp server will reside, should be looked at, to achieve this kind of optimization.

Any ideas where I should start looking besieds this forum ? :-)

Thanks,

Henrique Silva

[Sridhar Bhaskarla]

Hi Henrique,

Look at "ndd -h" output. You can adjust the window sizes on HP too. Here the default TCP window sizes are 32k. I don't know how your application works but you can do some research by playing with them. Use ndd -set to set the values and -get to get the values.

-Sri

[Henrique Silva_3]

Thanks Sri.

One other question here. By playing with the tcp window size, I can achieve some gains with the ftp, but what drawbacks can I ran into as well, on other areas ? I just want to make sure I am not making one area worse in order to achieve better ftp performance.

Cheers,

Henrique Silva

[Shannon Petry]

Depends on what else is running. Any applications that require lots of data movement (FTP, NFS) will benefit from the larger window size. The default is setup for good performance for most apps, like DNS, HTTP servers, email, etc...

The changes made with ndd are not saved at boot time. There are a ton of threads dealing with ndd and maintaing settings at boot time, so I'll not re-write this information.

Regards,
Shannon