Maximum value of nfile, kernel parameter

[Trenta Angelo]

Hi all,

I???ve a SuperDome with 11 Cpu and 12386304 kbytes of Ram.
There is Oracle Server 7.3.4.0, and DCE 1.8.
There are four Application Server and many clients dce which are connecting
to this DB Server.

In attachement there is an Oracle Instance Summary.

our clients say that they had connecting problems, so we
changed our nfile parameter, that it was 12186.

We changed our kernel parameters:

Nfile=17123
Maxusers=1024
Npty=1024
Nproc=8212

My question is:
Is there a maxumum limit to nfile parameter?
I would like to know this value
if so, should I have other kind of problems upgrading this value of nfile?

Currently we are changing this value with small steps, waiting for
our clients interaction, maybe we should take it to the maximum in only one step,
I appreciate suggestions to this way of proceeding,

Regards, Angelo

[eran maor]

Hi

nfile
nfile defines the maximum number of files that can be open simultaneously, system-wide, at any given time.

Acceptable Values:
Minimum 14
Maximum Memory limited
Default
((16*(Nproc+16+MaxUsers)/10)+32+2*(Npty+Nstrpty)

Specify integer value or use integer formula expression. For more information, see Specifying Parameter Values.

Description
nfile defines the maximum number files that can be open at any one time, system-wide.

It is the number of slots in the file descriptor table. Be generous with this number because the required memory is minimal, and not having enough slots restricts system processing capacity.

you can also check this link for details for kernel param : http://docs.hp.com//hpux/onlinedocs/os/KCparams.OverviewAll.html

and there is no problem to increase the vaule of the nfile in your computer

[U.SivaKumar_2]

Hi,
A relevant thread:-http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xc26d7bb04b5cd611abdb0090277a778c,00.html

regards,
U.SivaKumar

[James R. Ferguson]

Hi:

The limit for 'nfile' is memory-limited. The memory required to track large values is small, so you can increase this without problem. By default, the value is computed as:

((16*(nproc+16+maxusers)/10)+32+2*(npty+nstrpty+nstrtel)

If you wish to disregard the foumula and specify a hard-value, that too is acceptable.

Remember that you can use 'sar -v' or 'glance's table metrics to monitor 'nfile'.

Regards!

...JRF...

[Steven Sim Kok Leong · Accepted solution]

Hi,

The maximum is limited by the available memory. You can give a very large number because the required memory is minimal.

Every process uses at least three file descriptors per process and each process requires two pipes per process.

If you have glanceplus installed, you can check the current number of file descriptors being opened from the system tables and monitor its usage (an alternative way is to use adb).

Hope this helps. Regards.

Steven Sim Kok Leong

[Steven Sim Kok Leong]

Hi,

In addition to the kernel parameters you mentioned, related parameters you would want to verify would be maxfiles, maxfiles_lim and maxuprc.

While nfile is meant system-wide, maxfiles set the soft limit (and maxfiles_lim the hard limit) for the number of files a process is allowed to have open simultaneously.

nproc defines the maximum number of simultaneous processes on the system. maxuprc defines the maximum number of simultaneous processes available to each user on the system. Because the Oracle userid is used to start up multiple processes (a huge number especially in Oracle dedicated server architecture), then it is important for you to increase maxuprc along with nproc. maxuprc's max is nproc - 4.

Hope this helps. Regards.

Steven Sim Kok Leong

[Trond Haugen]

Generaly you can find documentation on kernel parameters from the help menue in SAM (while tuning the parameters).

Regards,
Trond