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Re: DBWR slaves in NT???

From: Paul Drake <>
Date: Thu, 01 Mar 2001 22:22:40 -0800
Message-ID: <>

just to clarify the earlier point (which failed to realize that slave processes were being discussed)

Windows NT supplies its own I/O slaves and uses them to see if I/O is complete.

from the 8.1.6 docs:

Initialization Parameters: Multiple Database Writers

 See: Appendix B, "Oracle8i Database Specifications for Windows NT"

You can specify more than one database writer process with the initialization parameter DB_WRITERS.

Multiple database writers can help, for example, when a UNIX port does not support asynchronous I/O.

DB_WRITERS, which writes dirty buffers to disk, is not supported. Windows NT supplies its own I/O slaves and uses them to see if I/O is complete.

Multiple DB_WRITERS might cause synchronization problems.

Initialization Parameters Without Windows NT-Specific Values:

DB_WRITER_PROCESSES                   Not applicable or necessary on
Windows NT.


Paul Drake wrote:
> Hi.
> multiple DBWR processes are not supported on NT and can lead to
> corruption.
> (check the platform specific release notes - I read it in the 8.1.7
> notes).
> I have the errors in the alert log to prove it - on a developement
> server.
> 2 CPUs, 2 I/O channels, 6 drives and 1 DBWR process. Not exactly
> balanced.
> Can anyone else see an O'Reilly book in the works - Oracle on NT
> annoyances?
> Paul
> I think that you should ask Joe Testa as to the upgrade path ...
> Raghu Kota wrote:
> >
> > Hi Friends
> >
> > I have toad tool for my NT database
> >
> > DBWR Average Scan Depth 1024 **Number of DB_Files too high??
> >
> > I got doubt due to from v$waitstat I got data block waits some time 8000 and
> > some times higher number. How can I increase the DBWR slaves on NT??
> > although I set in development box, How can I see as background process
> > really working for me??
> >
> > I have my datafile and indexes same on E disk drive, My hit ratios are okay,
> > My import is killing me.
> >
> > Any help appreciated.
> >
> > Thanks
> > Raghu.

Please see the official ORACLE-L FAQ:
Author: Paul Drake

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Received on Fri Mar 02 2001 - 00:22:40 CST

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