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some performance questions about running oracle on solaris

From: chao_ping <>
Date: Wed, 16 Apr 2003 08:33:42 -0800
Message-ID: <>

hi, list friends:

	I ever read some whitepapers, blueprints and document about manage/tune oracle on solaris, and tested some of them, and I have some questions:
	1. Is directIO really much better than buffered IO? I ever remounted my vxfs from buffered IO to directIO, and checked the iowait, cpu used from my cron log, I did not get any difference in the log. What about your experience?
	2. What other parameters do you tune in the /etc/system? I always set the shmmax to my physical memory and adjust the semmni to make oracle work, but what about others, like maxpio or vol  Does the parameters really have a measuable good performance impact?
	3.When using vxfs, do you use default blocksize? And what is the blocksize of vxfs, the result of "df -g"  or perl script result? (fstyp tells me it is 1k, the blocksize, while perl script and df -g tells me it is 8k). And which size is better, 1k or 8k? any measuable difference?
	4. If you have a database about 60g-100G, and disk array with size of 255G(Raid10), will you choose one big filesystem/one big volume, or tens of small volume/filesystem?  I argued with another dba that one big filesystem is easier to setup/maintain with no performance lost and we can dynamically enlarge the filesystem as we use vxvm and vxfs. What about your experience?
	5.When do you think that your server is running out of CPU capacity?  I read some manual/paper, some says that if your system is running user%+sys% > 80, then you should consider adding more cpu power to your system (IBM redbook), while others say unless the vmstat run queue is larger than 2*CPU_COUNT in your system, it is ok with the capacity of your system's cpu power.what about your experience? 
	Thank you for reading such a lengthy question and if you are interested, please share your experience with us.

zhu chao                                    

          2003-04-16      mni


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Author: chao_ping

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