topic kernal tuning in Operating System - HP-UX

kernal tuning

dinil — Tue, 15 Nov 2005 10:31:16 GMT

problem reported: Very often the database (mfg/pro) throws out users. Some times database get shuts automatically with the following error messages.
the following log file is attached
find or open file /gillive/giltrad.bi, errno = 23. (43)
11:00:28 Usr 2: SYSTEM ERROR: Unable to get file descriptor for /gillive/giltrad.bi (5338)
11:00:28 Usr 2: Could not open /gillive/giltrad.bi. Error = -1 (5311)

This UNIX error indicates that the number of files allowed to be have been opened and the NFILES or NOFILES OS
kernel parameter has been exceeded .They suggested to increase the NFILES or NOFILES kernel parameter.
The error requires an increase and regeneration of the UNIX kernel.

i tried toincrease the value of NFILES inorder to sort this problem
i also tried for performing Kernal Tuning operation and no such parameters were found through SAM (kernal Parameters).
the entries in through SAM is also attached along with this mail.
Earlier kernel tuning were carried out and "nfile " parameter were found .so we booted server through previous kernal (/stand/vmunix.prev) Still problem persists.

i also tried to do kernel tuning manually through command line,afterall we were not able to increase the value for "nfiles".

So please suggest us a solution for increasing the values of NFILES

Re: kernal tuning

Luk Vandenbussche — Tue, 15 Nov 2005 10:36:39 GMT

Hi,

change the paramter for nfile in /stand/system

Then excute the following command

mk_kernel
kmupdate
shutdown -r 0 (to reboot your server)

After the reboot the new nfile paramater must be active

Re: kernal tuning

Raj D. — Tue, 15 Nov 2005 11:25:52 GMT

Hi Dinil ,

Here is a simple step to increase the value nfiles :

( make sure you have old kernel file , i.e vmunix.prev else keep a copy of that )

Ex: If you want to increase nfile value from current value of 4024 (suppose)

# kmtune -s nfile=8024
# ./mk_kernel
# ./kmupdate
# shutdown -r -y 0

after reboot check new kernel parameter for nfile
# kmtune -q nfile
or
# kmtune | grep nfile

Enjoy,

hth,
Raj.

Re: kernal tuning

Ted Buis — Wed, 16 Nov 2005 07:42:13 GMT

The kernel parameter "nfile" is automatic tuned in HP-UX 11.23, so if that is what you are running then you won't have it. But I really think that your not looking to tune the right parameters, since nfile is the max number of in-core inodes, not the maximum number of open files. The kernel parameter "maxfiles_lim" is the hard limit for maxfiles and it is dynamically tunable. The maxfiles is the soft limit for the number of open files, but there are software calls to increase it as needed up to the hard limit of "maxfiles_lim".

ted

Re: kernal tuning

Orhan Biyiklioglu — Wed, 16 Nov 2005 07:51:28 GMT

You have to change the maxfiles and maxfiles_lim parameters since these parameters limit how many files should a process open.

# kctune -v maxfiles
Tunable maxfiles
Description Initial (soft) maximum number of file descriptors per process
Module fs
Current Value 2048 [Default]
Value at Next Boot Default (automatic)
Value at Last Boot 2048
Default Value 2048 (automatic)
Constraints maxfiles >= 32
maxfiles <= 1048576
maxfiles <= maxfiles_lim
Can Change At Next Boot Only

# kctune -v maxfiles_lim
Tunable maxfiles_lim
Description Hard maximum number of file descriptors per process
Module fs
Current Value 4096 [Default]
Value at Next Boot 4096 [Default]
Value at Last Boot 4096
Default Value 4096
Constraints maxfiles_lim >= 32
maxfiles_lim <= 1048576
maxfiles_lim >= maxfiles
(2 * maxfiles_lim) <= nfile
Can Change Immediately or at Next Boot

Try increasing them

kctune maxfiles=
kctune maxfiles_lim=

and reboot your server.

hth