Increasing nfile kernel parameter

[Mark Aldous]

hi,

Been through the forums and hoping you can help. We've been getting some vmunix: file : table is full errors and increased maxusers but still got the error. The database guys have now pinpointed what value we need and say nfiles needs to be 40,000 (currently 13,449). When making smaller changes I've increased maxusers but its currently 800 and would need increasing to 2300! I'm concerned what effect increasing max users to the new value will have on other parameters and memory use (did a change in sam to view other values and nkthread would exceed max)? would it be ok to just raise nfile?

I'm currently running on v11 with 5Gb memory.

i'd be grateful for any advice. Thanks

[Pete Randall]

Mark,

You don't necessarily need to increase maxusers - just plug the value you need into nfiles.

Pete

[Vicente Sanchez_3]

Hi,

In my opinion you should only modify nfile parameter rather than maxusers. This parameter modifies other kernel values that can not be needed change.

Regards, Vicente.

[Ashwani Kashyap]

Just change the values of nfile to what you want . There is a formula associated with it and it would automatically change the values of other related parameters like , nproc , maxusers ,npty etc .

[Mark Aldous]

Many thanks for your replies. I just saw on one thread that they recommend increasing nflocks as well as nfile. Any point in this?

[James R. Ferguson · Accepted solution]

Hi Mark:

'nfile' governs the limit on the number of open files, system-wide. 'nflocks' controls the limit on the number of file locks, system-wide. There is not necessarily a correlaton between these. I'd increase what you need as you need it.

You can monitor 'nfile' and 'nflocks' with 'glance's [t]able view.

Regards!

...JRF...

[Pete Randall]

Mark,

I'm not sure there's a clear answer, other than "it depends". From SAM's HELP on configurable parameters:

Open and locked files consume memory and other system resources.
These resources must be balanced against other system needs to
maintain optimum overall system performance. Achieving an optimum
balance can be quite complex, especially on large systems, because of
wide variation in the kinds of applications being used on each system
and the number and types of applications that might be running
simultaneously, the number of local and/or remote users on the
system, and many other factors.


My production machine, for example, has nflocks set to 200, while nfiles is 4468.

[Mark Aldous]

Many thanks, I'll just increase the nfile and see how we go.