Solution for Memory pressue in HP UX

[Shankar Palaniappan]

We have a recent problem with one of the process in HP-UX, where the important process which handles database management is deactivated due to memory pressure for particular duration

My question is do we have any solution for memory pressure in HP-UX.

[Analyst]

Hi Shankar,
>:My question is do we have any solution for memory pressure in HP-UX

what is means,

1.Swap memory utilization
2.physical memory utilization
3. particular Process utilizing more memory.

explain us with the some more details to solve the issue.

Thanks,
Analyst.

[Shankar Palaniappan]

Thanks and I am impressed with your immediate response.

[Shankar Palaniappan]

Thanks once again.

Here is the detailed view of the problem.

we got problem related to performance issue from one of the customer. From the logs of database management process, we came to know that the important process, which handles database management has not shown any logs for particular duration and we gone through HP-UX forums and came to know that due to memory pressure, HP-UX will deactivate the process, which consumes more memory at that time. During this time, messages which come to database management process (daemon) is lost and we have reported the customer that due to memory pressure the appropriate process is deactivated since it consumes more memory.

As we have to give solution for the memory pressure, I have raised the same in your forum. From your previous reply, I came to know that we have to analyze the physical and swap of reported HP-UX and we have to give the option to increase the same.

Please clarify my opinion if my view to previous mail is wrong and also let me know do you have any other link for tuning swap and physical memory of HP-UX other than the following link

http://docs.hp.com/en/1219/tuningwp.html

Thanks once again for your immediate response.

[Analyst]

Shankar,

Good to get a detailed reply.

yes you can goahead in tuning the parameters.

1.Check for the availablity Hradware/Logical resources,
2.Do the modification as best practice.
3.Make sure the impact of the business before the modification.
4.Feel free to post the thread ,incase of errors.

Thanks,
Analyst.

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[Dennis Handly]

There may be several solutions to memory pressure:
1) Install more memory
2) Use less memory, less processes, less SGA, less disk cache.
3) Use less memory in this important process, or lock its memory?
4) Possible patches for bad HP-UX handling?

Have you tried using glance to see what's happening during this time?

[prasadb]

hi shankar,
can you post the o/p of
1.glance -m

[prasadb]

also, #vmstat 1 5

[Shankar Palaniappan]

The reported problem happened on customer site and it is not happening quite often, it roughly happened two times so far in couple of years. For me it will take some time to get the output of
glance -m
and vmstat output

Thanks for prompt and immediate response

[Ganesan R]

Hi Shankar,

Process deactivation will only happen when system runs out of physical memory. There is a predefined memory thersold value called "desfree" in the kernel. When the free physical memory falls below the value defined by desfree, then system deactivates some processes and puts them on hold. The memory pages allocated to these processes are swapped out of memory and are marked free in the page table. The swapper daemon reactivates these processes when conditions favorable to run these processes have returned.

So it is clear that, your system is running out of physical memory. You need to find out how much physical memory actucally needed to run all applications and system has that amount or not.

Sometime, improperly coded applications may consume more memory. In this case, you need to work with application vendor to fix the application issue.

You can also check, how much memory is consumed by system process. Sometime improperly tuned system may consume memory unnecessoryly. Check buffer cache values specically(dbc_min_pct and dbc_max_pct)

If you find all are ok, the only way is put addition memory into the system.