Impact of raising maxfiles_lim on HP-UX11

[Jaris Detroye]

Currently SAM limits maxfiles & maxfiles_lim to 2048. What is the impact (besides the obvious) to the kernel & the system in general of raising this very high? I have an e-mail server, and the software provider is recommending that maxfiles_lim be set to 60000 or higher.

Is there a down side to doing this?

[MANOJ SRIVASTAVA]

Hi Jaris

What you are talking is maxfiles_lim per process:

maxfiles_lim
This sets the hard limit for number of files a process is allowed to have open. The default for this kernel parameter, and our recommendation, is 2048.

I ahve not seen this limit to be utilized to the full .

I think the s/w engineer should look into to the sendmail configurations.

Manoj Srivastava

[Jaris Detroye]

I am not using sendmail, it is a commercial product. And, on docs.hp.com on the HP-UX11 OS docs says the limit on this value is in fact 60000. I was just told by HP that the 2048 limit is a known problem and that the 60000 is correct.
Problem solved...

[Bill Hassell]

Changing maxfiles_lim has no direct effect on HP-UX. It is a fence, a limit against bad programs. Just like maxdsiz, a bad program could open thousands of files, HP-UX would hit the nfile limit for the entire system and not even root would be able to login--not good.

As you might expect, any program os the system will be able to open 60,000 files with maxfiles_lim set to 60k. Note that even if only properly behaved programs open this many files, nfile must be at least as large as all the open files. Assuming 10 programs opening 60k files, nfile set to 600,000 will have a serious impact on system performance.