From Glance to See Performance

[Steven Chen_1]

Hi,

I have hpux11i on K260 with 1G memory mostly used for Oracle8i. By looking at Glance, I see some paging in/out.

Would someone help to see if there is anything all right or need to tune on system/database memory utilization?

Very appeciated.

Steven

[Sridhar Bhaskarla]

Hi Steven,

Couldn't open the attachment.

Check your dbc_max_pct. If it is set to the default value of 50%, you may want to lower it to use around 300-400 MB of memory.

-Sri

[Krishna Prasad]

Steven,

Did you use pkunzip on your attachment?

[Krishna Prasad · Accepted solution]

From the glance output you attached I can tell that dbc_max_pct isn't your problem.

I see that the system is using just about all your memory and you are paging somewhat. However, I also saw that your CPU was at 92% with in the last 15 min. Do you know what your load is at. You can see this using the command top. If it is over 2 I would be concerned. It looks like your memory shortage is starting to push you CPU(s) a bit. Do you know what your SGA is set to in Oracle. You may need to increase/decrease this value depending on what it is set to. Also how many users are using the system.

In general it looks like you might benifit from a memory upgrade if it is in the budget.

[Mladen Despic]

Steven,

Your glance screen does indicate that memory is under pressure. You could configure Oracle to use less memory, but how large is your database? The chances are Oracle will need more memory for performance reasons.

If you do lower memory requirements for Oracle, you may still have problems if there are any processes leaking memory. You can monitor memory utilization by individual processes in Glance.

In any case, I would suggest adding more physical memory if at all possible.

[harry d brown jr]

Here's the unzipped attachment:

One thing I noticed is that you are utilizing 99% of memory.

live free or die
harry

[Steven Chen_1]

Thanks for all the great help!

I see sys mem is 281M, and buf cache is 15% of 51M. The rest mem is for Oracle of 668M. Oracle db is 6G (dat files for data and index). I know physical mem is in shortage. Unfortunately I can't control the budget.

So do I have some paging? Does that means too much mem put on SGA (oracle mem) now, or too little?

Continal help is appreciated.

Steven

[harry d brown jr]

Steven,

What kind of storage are you using for oracle - Raw vs filesystem? You can, and I have over 400 hp 9000's set this way, change your db_max to 10%, your min should also be around 5%. Giving you 10% of a gig, which is 100mb, usually more than adequate for filesystem handling.

btw, I took your bmp file and reduced the size by changing the bits from 24 to 16.

live free or die
harry

[Sridhar Bhaskarla]

Hi,

I can open Harry's attachment.

Not only you are paging out, but there are some deactivations also. Interestingly you are not doing much of disk I/O. So, I would suggest so lower your dbc_max_pct further down.
You may want to check the glance again during times when your system is heavily loaded. You will get a good idea from there.

-Sri

[Steven Chen_1]

Thanks again for the help.

We are using filesystem for Oracle, no raw.

I see buffer cache only uses 50M (min 5% of 1G), but don't know if I lower dbc_max_pct from 15% to 10% recommended here, would the system mem usage of 280M be reduced? Or what else we can "save" from?

Appreciated.

Steven

[Krishna Prasad]

Steven,

What is your Oracle SGA set to. If it is to low it could be causing your paging becuase Oracle's needs more shared memory. It is also possible that it is set to high not leaving enough physical memory for Oracle clinet connections.

You can find out by looking at your initSID.ora file.

Also, what is your Oracle hit ratio this is a good indicator for the correct setting for your SGA. If you are getting less then 90% hits the SGA needs to be adjusted.

[Bill Hassell]

For Oracle, the size of SGA (specifically, Oracle's buffer cache, shared pool, temp pool, etc) directly affects performance. Page out is the ONLY stat you pay attention to since page in also counts every new process that starts.

If page out is 5-10 in Glance, you're fine. If it starts pushing 30-50, then performance will suffer. Since you are limited in RAM by budget constraints, there is nothing you can do as a sysadmin. However, most sysadmins and seasoned DBAs will agree that rewriting poor SQL statements and/or adding new indexes will help performance more than kernel tweaking. Note that Oracle silently ignores indexes that are badly out of balance...it's a good idea to rebuild those indexes regularly when lots of row insertions are being done. These indexes can be created very fast by using the old index to build a new one rather than deleting and creating the index.

[Steven Chen_1]

Again thanks all for the in-depth analysis.

Question for Bill & Harry:

1) among columns in mem Glance graph, which worths looking on "page out", Current, Cumulative, or High Rate...?

2) dbc_min_pct is set to 5% and at peak it keeps on there of 51M. So changing dbc_max_pct from current 15% to 10% does little about it. Is that right? Or put it this way, hpux11i needs 280M to work in this case?

Thanks,

Steven

[Sridhar Bhaskarla]

Hi Steven,

As I mentioned before, we can see some deactivations happening on your system. On a 11.0, the deactivation occurs typically after reaching the "minfree" limit. So, you would want to check the rate of page outs and deactivations when your system is heavily used. Also, your swapinfo -t and the KB used (only on the swap devices not the reserve or memory rows) in it will give you how much is sitting in your swap areas.

I don't know how much it is going to help you but you can bring down some of the processes like NFS, sendmail, lp daemon etc if you are not using them. Also install the lastest possible patches and diagnostics.

-Sri