nflocks - any issues with raising this value?

[gino castoldi_4]

Hi,

HP-UX 11.0 VPO 6.14 NNM6.2 Oracle 8.1.7.3
MC/SG 11.09 4GB memory

Our current 'nflocks' value is 250. we want to raise it higher (say to 4096) because we had
file lock issues. Will a value of 4096 be ok?

10 points to any good answer.
Thank you
Gino

[RAC_1 · Accepted solution]

No issues with that. This is just no. of file system locks.

Just check if it has any dependencies on other kernel parameter.

[Jeff Schussele]

Hi Gino,

As most questions can be answered - It depends.

Running Oracle and NNM 250 would be way too low. What's your nfiles parm set to? But keep in mind, 1 file can have several locks and if your Oracle apps use lockf() call, you could need quite a bit.

Keep in mind that file locks use system memory so IF you do set 4096, get an idea of memory usage now, pre-change & compare it to post-change.

HTH,
Jeff

[Helen French]

Setting the right value for nflocks (or any other kernel parameter) will depend up on the system usage. But the value 250 is too very low for your setup. The best value for your environment can be achieved by trial and error method. Check your resourse usages before and after changing the value. Once you do that couple of times, you can set the proper values for the Kernel parameters.

To answer your question, increasing this value to 4096 should not create any issues.

[Cheryl Griffin]

You could monitor nflocks usage with lsof:
# lsof | awk 'match("NrRwWuUx",substr($0,31,1))'|wc -l

[gino castoldi_4]

Hi Cheryl,

I ran the lsof command with the awk options and it returned nothing.

10 points for any good answer.
Thank you
Gino

[Todd McDaniel_1]

I have a fairly large system, superdome 48-way, with 72gb of memory... I had to increase mine b/c DB size and use recently doubled...

My original nfloks was at 57000 but I increased it to 85000 with no problems.

And then last week, I increased it again to 100k...

The only restriction im aware of is memory as with most kernel parms.

[Cheryl Griffin]

Gino,
You should have gotten back a number.

I double checked the command and got an error without specifying the full path.

Changed the command to:
# /opt/lsof/bin/lsof | awk 'match("NrRwWuUx",substr($0,31,1))'|wc -l

which did show me valid results.
The wc -l gives a line count.


You could leave that off and use:
# /opt/lsof/bin/lsof | awk 'match("NrRwWuUx",substr($0,31,1))'

[Dave Hutton]

You probably do not have lsof on your server, so that is why you didn't get any value back. You may have to download it which is at:
http://hpux.cs.utah.edu/hppd/hpux/Sysadmin/lsof-4.69/

Dave