Not sure what you mean by "I/O points". Whether or not multiple DB writer will be of benefit to you depends on a couple things.
First of all, can you use async IO? I don't see any mention of what platform you are on. If you're using Windoze, it is async IO by default. Async IO is generally a better choice, and there is then no need for multiple DB writers. If aync is not used, then can use multiple DB writers. The number of IO cards is not directly related to whether multiple DB writers should be used, but rather, what is the bandwidth of the IO system. If you have 5 filesystems, each with a max throughput of 100 IO's per second, and your IO card has a throughput of 500 IO's per second, your system will underperform during periods of heavy activity if only 1 DB writer is available. I seem to recall Oracle docs saying that up to 2 DB writers per filesystem as a max value. This of course depends on your CPU and memory constraints as well. If I had my 'Oracle Tuning 101' from Gaja and Kirti in front of me, I would just quote from it, but it is unfortunately at work, and I'm not. Just do a little homework, say 'yes boss', and do what's best. And of course, just use async if possible, it's a lot easier. HTH Jared On Tuesday 03 June 2003 06:01, [EMAIL PROTECTED] wrote: > you only want DBWR_IO_SLAVES or multiple DBWRn if you have datafiles spread > over multiple I/O points correct? We are using 'Network Appliance' hard > disk array that Im not all that familiar with. It looks like we have 3 I/O > points and 5 mount points. > > my boss told me that striping data files and redo log files across the I/O > points wotn help because there is only 1-2 I/O cards(forget the exact, I > hope it isnt hard for anyone to figure out what Im referring to) on the > server itself. > > This does not sound accurate. Since Ive read several books and all say to > stripe the files? > > btw, thanks for the info on the large pool. I can free up about 300MB of > memory we aer wasting on that and the java pool for other areas. > > > From: Mladen Gogala <[EMAIL PROTECTED]> > > Date: 2003/06/03 Tue AM 07:39:41 EDT > > To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > > Subject: Re: question about large pool > > > > Well, I was talking about cursors, sort areas and hash areas. I probably > > did confuse "GA stuff". > > > > On 2003.06.02 22:27 Tim Gorman wrote: > > > Almost. It is the UGA areas (not the PGA) for Shared Server (a.k.a. > > > multi-threaded server) that are re-located to the Large Pool, if it > > > exists. Otherwise, they reside in the Shared Pool and all hell breaks > > > loose, performance wise... > > > > > > Also, if DBWR_IO_SLAVES > 0, then those IPC queues will reside in the > > > Large Pool, if it is configured. Otherwise, these reside in the Shared > > > Pool, and if you think having UGAs from Shared Server in the Shared > > > Pool play hell with performance, then wait until you are pushing all of > > > your I/O to the datafiles through the Shared Pool... :-) > > > > > > on 6/2/03 2:24 PM, Gogala, Mladen at [EMAIL PROTECTED] wrote: > > > > Nope, it's not accurate. PGA areas for shared server sessions are > > > > also allocated from the large pool. > > > > > > > > Mladen Gogala > > > > Oracle DBA > > > > Phone:(203) 459-6855 > > > > Email:[EMAIL PROTECTED] > > > > > > > > > > > > -----Original Message----- > > > > Sent: Monday, June 02, 2003 4:35 PM > > > > To: Multiple recipients of list ORACLE-L > > > > > > > > > > > > for some reason we have 100MB large pool. I dont think we need it at > > > > all. I read that its only used by RMAN or Parallel server. Is that > > > > accurate? > > > > > > > >> From: DENNIS WILLIAMS <[EMAIL PROTECTED]> > > > >> Date: 2003/06/02 Mon PM 03:39:42 EDT > > > >> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > > > >> Subject: RE: question about large pool > > > >> > > > >> Use the large pool to store what? I can think of 3 aspects of a > > > > > > > > transaction: > > > >> - Rollback (you've probably read about SET TRANSACTION) > > > >> - SQL statements, execution plans (more an issue with bind > > > >> variables) - Data blocks > > > >> It sounds like you might be thinking of data blocks. You didn't > > > >> mention > > > > > > > > your > > > > > > > >> Oracle version, but from 8i on you can define 3 buffer pools. The > > > >> normal > > > > > > > > one > > > > > > > >> is DEFAULT. You can also define a KEEP and RECYCLE pool. Someone on > > > >> this list (sorry I can't recall who) pointed out that there isn't > > > >> anything > > > > > > > > magic > > > > > > > >> about those labels. If your transaction uses different tables from > > > >> the > > > > > > > > other -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Jared Still INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
