Re: db writer working data sets
- From: Taral Desai <taral.desai@xxxxxxxxx>
- To: Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>
- Date: Wed, 10 Jun 2009 10:51:13 -0500
May be of interest http://forums.oracle.com/forums/thread.jspa?messageID=3528668 On Wed, Jun 3, 2009 at 9:32 AM, Taral Desai <taral.desai@xxxxxxxxx> wrote: > Also sorry it's my bad forgot to include vital information. DB is 10.2.0.3 > and OS is solaris 10 sparc 64 bit. We are using SAN for storage > > > On Wed, Jun 3, 2009 at 9:14 AM, Taral Desai <taral.desai@xxxxxxxxx> wrote: > >> Thanks Greg, >> I got your point. Well, what about my first 2 questions. How do i find >> that information. >> >> >> On Wed, Jun 3, 2009 at 12:35 AM, Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>wrote: >> >>> Unless "free buffer waits" is in your top 5 wait events in >>> AWR/Statspack, you dont need more db writers. In almost all cases, >>> the default value for db_writer_processes is sufficient. >>> >>> http://download-west.oracle.com/docs/cd/B28359_01/server.111/b28274/instance_tune.htm#sthref759 >>> >>> Tuning "buffer busy waits" is different. You need to find out what >>> what type of buffer is being waited for and triage why. >>> >>> http://download-west.oracle.com/docs/cd/B28359_01/server.111/b28274/instance_tune.htm#sthref657 >>> >>> As a data point, the recent TPC-C that Oracle published >>> http://tpc.org/tpcc/results/tpcc_result_detail.asp?id=109052101 >>> used a db server that has 72GB RAM, multiple block caches (2k/8k/16k) >>> and 1 CPU (quad core Intel 5520 "Nehalem") and did over 230k tpmC >>> using a single db writer. >>> >>> On Tue, Jun 2, 2009 at 2:50 PM, Taral Desai <taral.desai@xxxxxxxxx> >>> wrote: >>> > Reason behind this we are using 12 dbwriter process for we have 12gb of >>> sga >>> > and 10gb of pga. Some time we are getting buffer busy waits. So, need >>> to >>> > find that we are using multiple buffer pools. So, if it is from there >>> then i >>> > can suggest management to use only default block size and not multiple. >>> I >>> > already know that multiple buffer pool have overhead >>> > of managing one more memory structure so need to investigate and learn >>> from >>> > you. >>> > My idea is to reduce this and then start adding processes if necessary. >>> >>> >>> -- >>> Regards, >>> Greg Rahn >>> http://structureddata.org >>> >> >> >> >> -- >> >> Thanks & Regards, >> Taral Desai >> > > > > -- > > Thanks & Regards, > Taral Desai > -- Thanks & Regards, Taral Desai Woody Allen <http://www.brainyquote.com/quotes/authors/w/woody_allen.html> - "Money is better than poverty, if only for financial reasons."