nfs_do_purge_rddir_cache setting for 11.11

[Robert_Jewell]

Have a situation similar to the one described in doc: emr_na-c00916366-4
http://www13.itrc.hp.com/service/cki/docDisplay.do?docLocale=en&docId=emr_na-c00916366-4

The issue is that the memory arena M_NFS_GEN is utilizing a large portion of dynamic memory:

----------------------------
Dynamic = 821586 3.1g 78% Kernel dynamic memory
Arenas = 750193 2.9g 72% Kernel arenas
M_NFS_GEN = 688334 2.6g 66%
M_TEMP = 23023 89.9m 2%
----------------------------

The document describes this and advises to change the kernel setting nfs_do_purge_rddir_cache so that purging of this cache is active. The OS is 11.11 and the document states the following:

" Since the nfs_do_purge_rddir_cache kernel parameter is
"invisible" on HP-UX 11.11, HP recommends that you contact
your local HP support center for instructions on how to
change/set this parameter's value. "

I have not been able to locate any such procedure though. So my question is how do I make such a change to see if it affects the server in a positive manner (i.e. by not becoming unresponsive).

Thanks and regards,
Bob

[Dennis Handly]

>I have not been able to locate any such procedure

Have you contacted the Response Center?

[Robert_Jewell]

Well, no. I was trying to avoid explaining the situation to three different RCE's before getting what I am looking for. Ill go that way of course, but was hoping for some insight from someone who has gone through this already.

-Bob

[Dave Olker · Accepted solution]

Hi Bob,

The problem is since this variable is not exposed on 11.11, the only way to change it is to use a kernel debugger to locate the address of a data structure that references this variable in kernel memory on the live system and then "poke" it to 1. As you might imagine, this is a very dangerous procedure and is highly prone to error (i.e. if you write a "1" to the wrong area of memory or your kernel.......bad things can happen).

If you really want to try this your best bet is to open an RC call and they'll probably have someone from WTEC help make the change. This change would likely only work until your kernel is rebuilt or a kernel patch is installed because then the location in the kernel will undoubtedly change.

Another option - update to 11.23 or 11.31 where this variable is tunable via kctune. I know...easier said than done... but I can say there are tons of other NFS client improvements in 11.23 and 11.31 that make it attractive to update an 11.11 NFS client.

Regards,

Dave

[Robert_Jewell]

Dave - thanks for the clarification. I had not understood what was involved and appreciate the info.

Regards,
bob