problems with db_writer_processes parameter

[ckiltz]

Hallo,

my DB is running with two CPUs. For more efective writing data to RAID 5 discs I try to start 4 db_writer_processes. I can start 2 but not 4 of them. Is there any rule I do not now?

Please help me! Christian

Oracle9i Release 9.2.0.1.0 - Production
PL/SQL Release 9.2.0.1.0 - Production
CORE 9.2.0.1.0 Production
TNS for 32-bit Windows: Version 9.2.0.1.0 - Production
NLSRTL Version 9.2.0.1.0 - Production

[OracleDoc]

Hallo aus Heidelberg!

go check out this on meta link it should answer your problem

[ckiltz]

Hallo aus Berlin ;-)

I can´t open this link. How can I get an Oracle Support contract or the artikel?

Thank you for help!

Christian

[engiri]

Originally posted by ckiltz
Hallo,

my DB is running with two CPUs. For more efective writing data to RAID 5 discs I try to start 4 db_writer_processes.

raid 5 ?? immmm very bad for performance.
Last month only I say BYEBYE to Raid 5.
Now in 0,1.
Sleeping well in night.
consider changing 5.

[OracleDoc]

in order to access metalink you have to have a CSI number. Whomever bought Oracle at your shop would have this information. Simply goto http://metalink.oracle.com and register an account there. It takes all of about 5 minutes to do.
If you don't have a CSI number reply back here and I'll cut and paste the note.

[ckiltz]

Originally posted by engiri
raid 5 ?? immmm very bad for performance.
Last month only I say BYEBYE to Raid 5.
Now in 0,1.
Sleeping well in night.
consider changing 5.

... It was not my decision to take RAID 5. I red in "Oracle9i Performance Tuning" RAID 5 is slow in writing but fast in reading in combination with Oracle.

Greetings from Christian

[engiri]

not all the oracle files in 5.
isn't it?

[ckiltz]

Sorry but I don't have a CSI number.

I only have to eMail Oracle and get one?

Christian

[DaPi]

If your redologs are on RAID-5, moving them to RAID-1 or multiplexed non-RAID will probably help more than more db writers.

[marist89]

You can only have as many dbwrites as you have db_block_lru_latches. Check this parameter and increase through your init.ora if necessary. However, bumping your dbwrites past 2 on a 2 cpu box will make them compete with each other if you in fact dbwriter can't get enough CPU already AND your on non-async filesystems.