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Re: swapinfo -tam HIGH (dbc_max_pct=50)

 
Rita C Workman
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

1. You do not have enough swap set up to begin with. I recommend disk. Add two 4Gb lvols, and set each up as swapspace. I don't care if they are the same 8Gb disk.
2. If you left dbc_max_% at 50 (default) you likely left the rest defaulting.
20 on dbc_max is fine, you could probably go down to 15 safely.
Set dbc_min to 5
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Run sar -v 1 20
Look at the output of inode (current/parm)
Set parm ninode down to something more realistic based on the output of 'sar'. For my oracle systems I have them around 4096.
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maxdsiz
I don't care what Oracle says...bet you can set that one back too! I have mine at 0X10000000 (268435456). They just need it turned up when they load s/w, but you do not have to keep it there.
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vx_ninode.
It's probably at zero (0), which means systems on 11.11 is controlling. It doesn't do it all that well. Try setting at 20,000 to 40,000. I have yet to hit the limit at 40,000. If you have 8Gb memory, this parm creates a huge table - and you're just wasting space.

ninode - creates a round-robin table that recycles inodes. That sar command will show you how much you need. Allow enough room for nightly batch processes if applicable. The default value the kernel will build is way-way bigger than you need. Thus, you are wasting memory.
vx_ninode - Again with too big a table and a version that the system doesn't manage that great. Set the value, so you don't waste mem.
dbc_max & min_%. These two default parms have been a known issue for years. There are a multitude of threads on this. Do a SEARCH, and you will be amazed.

These are just a couple of default parms to look at and fix right away. There are others, but it is best to just adjust as few as possible.

Remember -
Tuning is a journey taken in small steps.

Regards,
Rita
Rita C Workman
Honored Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

On that immediate change and oracle.

11.11 has very few parms, dbc_max_% will require a kernel rebuild, hence a reboot.

11.23 for dbc_max_% (and min) can be changed immediate - or next reboot.

11.31 for dbc_max_% is automatic and can be changed immediate.

As for Oracle...as when any reboot is required, just shut it down, do your parms (selectively), then bring it all back up. By doing it one parm at a time you can ensure that each parm works for you...or change it back. If Oracle comes down clean and is set up properly, you should be okay.
In fact - with the parms tuned better, Oracle should run better!

Rgrds,
Rita
Steven E. Protter
Exalted Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Shalom,

dbc_max_pct" which is 50 is the buffer cache.

Setting this to 50% is very high and allocates half of available memory to this cache.

You can substantially lower system memory use by setting this number to a lower figure. Databases like Oracle do a better job than the Os caching data, especially on the 11.11 OS.

SEP
Steven E Protter
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Akif_1
Super Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hi Rita,

Find below sar output:

xxxapp1:/ ABC#sar -v 1 20

HP-UX xxxapp1 B.11.11 U 9000/800 04/27/10

08:42:19 text-sz ov proc-sz ov inod-sz ov file-sz ov
08:42:20 N/A N/A 954/4096 0 2223/34816 0 15444/63498 0
08:42:21 N/A N/A 954/4096 0 2224/34816 0 15433/63498 0
08:42:22 N/A N/A 954/4096 0 2223/34816 0 15432/63498 0
08:42:23 N/A N/A 952/4096 0 2224/34816 0 15425/63498 0
08:42:24 N/A N/A 952/4096 0 2225/34816 0 15434/63498 0
08:42:25 N/A N/A 953/4096 0 2224/34816 0 15442/63498 0
08:42:26 N/A N/A 954/4096 0 2225/34816 0 15451/63498 0
08:42:27 N/A N/A 952/4096 0 2226/34816 0 15462/63498 0
08:42:28 N/A N/A 951/4096 0 2223/34816 0 15465/63498 0
08:42:29 N/A N/A 954/4096 0 2226/34816 0 15469/63498 0
08:42:30 N/A N/A 954/4096 0 2225/34816 0 15453/63498 0
08:42:31 N/A N/A 953/4096 0 2227/34816 0 15447/63498 0
08:42:32 N/A N/A 952/4096 0 2224/34816 0 15446/63498 0
08:42:33 N/A N/A 953/4096 0 2224/34816 0 15436/63498 0
08:42:34 N/A N/A 950/4096 0 2224/34816 0 15425/63498 0
08:42:35 N/A N/A 950/4096 0 2225/34816 0 15411/63498 0
08:42:36 N/A N/A 949/4096 0 2225/34816 0 15409/63498 0
08:42:37 N/A N/A 950/4096 0 2223/34816 0 15394/63498 0
08:42:38 N/A N/A 947/4096 0 2223/34816 0 15386/63498 0
08:42:39 N/A N/A 950/4096 0 2224/34816 0 15401/63498 0
T(ogether) E(very one) A(chive) M(ore)
Raj Briden
Frequent Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

You can go ahead and reduce the dbc_max_pct parameter to the value 25 and check the performance.

Akif_1
Super Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hello Raj,

My concern mainly with this two areas.

#Does this parameter effect oracle application server.
#How to revert back if kernel fail to startup server after new kernel buildup.

Regard's
T(ogether) E(very one) A(chive) M(ore)
Raj Briden
Frequent Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

i had reduced this paramaeter with out any issue.

Reboot the server before reducing this server to check server is booting fine.

Always have a good ignite backup!

Akif_1
Super Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hi All,

Even though after dbc_max_pct=20 value changed still memory usage is high.

The http process and forms connection increase considerably.

Need help to solve the issue.


Rgd's
T(ogether) E(very one) A(chive) M(ore)
Dennis Handly
Acclaimed Contributor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

>Even though after dbc_max_pct=20 value changed still memory usage is high.

You can decrease it to 5%.
Are you doing lots of swap outs?
Akif_1
Super Advisor

Re: swapinfo -tam HIGH (dbc_max_pct=50)

Hello Dennis,

You can decrease it to 5%.
Are you doing lots of swap outs?

#yes But my 8GB memory only have 800MB + /logs/paging 800MB swap which not possible to increase due to lack of FS space.

Any suggestion
T(ogether) E(very one) A(chive) M(ore)