nettune on the fly

[Tom Danzig]

Hi all,

Just to put my mind at ease ... any concerns on setting tcp parameters (specifically tcp_keepstart) on the fly while the server is up and running?

This is a Sybase DB server with lots of active connection. It's not part of a MC/SG cluster.

Any thoughts/concerns in doing this online?

Thanks,
Tom

[John Poff · Accepted solution]

Hi Tom,

You can do it online, no problem. I've done it before and it is really handy. The only concern is that you need to be absolutely sure that you understand what parameter you are changing and why, because you can make your life interesting in a hurry if you get it wrong! :)

Also, if you decide to make the changes permanent, you'll need to put them in the /etc/rc.config.d/nddconf file so that they will be set again when your system reboots the next time.

JP

[A. Clay Stephenson]

I assume this is a 10.20 box since you are using nettune rather than the newer ndd command. In any case, 'on the fly' changes should pose no problems.

[John Poff]

Oops. Forgot my signature for the day!

"Live free or die"

[Tom Danzig]

Thanks for the replies. Now I can relax.

It is a 10.20 system and the appropriate rc script is written and linked.

Happy Thanksgiving all.

[S.K. Chan]

Agree with all. Just one comment, check first if there exist such patch "nettune cumulative" on a 10.20 (if you're on 10.20). If yes, install that patch first. The reason why I mention this is that I do recall earlier version of 10.x which need such patch for better nettune reliability. Not sure if 10.20 has it.

[rick jones]

While it is fine to execute nettune (and ndd) commands on the fly, don't expect all of the parms to "take" for connections already established. Some settings are grabbed at connection establishement.

In the specific case of tcp_keepstart, I am not sure if the change would take effect for existing connections. It might, but then again, it might not.

Window/socket buffer size changes would not, I suspect that listen queue backlog changes would not.