RE: DBWR slaves in NT??? (speeding up imports)

Metalink Note:1023899.6 on IMPORT PERFORMANCE TIPS might offer some useful basic advice.
Also Note:93763.1 Tuning Considerations When Import is slow might be of use.

Rachel - I am aware that you can do a direct export, but my help under 816 (NT) for import doesn't mention a direct import option.

If you're VERY brave and this is a test instance (& you understand the implications) you might consider turning off redo generation to speed up the import.

Regards,
Bruce

-----Original Message-----
Sent: Friday, 2 March 2001 8:46
To: Multiple recipients of list ORACLE-L

um, dump indexes, do direct=true on the import and rebuild indexes....

>From: "Mohan, Ross" <MohanR_at_STARS-SMI.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: RE: DBWR slaves in NT???
>Date: Thu, 01 Mar 2001 12:40:38 -0800
>
>I agree. I focussed my answer almost exclusively
>on Raghu's last line. "My import is killing me."
>
>In my hazily-recalled modicum of experience, this
>probably has a simple solution.
>
>Or, hell, maybe I am wrong. It *could* require
>doing something slick and esoteric, like calling in
>Rivest from RSA to recalculate the prime number seed
>for the db_block_hash_fuckits parameter and then
>rewriting the kxscvngr subroutine in assembler
>to more aggressively clump and scavenge the dirty
>blocks in mode "1016" from the warm end of the
>buffer cache.
>
>But, I doubt it.
>
>- Ross
>
>p.s. Raghu, stay in touch, and tell us what you try,
>willya?
>
>
>-----Original Message-----
>Sent: Thursday, March 01, 2001 3:09 PM
>To: Multiple recipients of list ORACLE-L
>
>
>If I am completely off the wall here just slap me around a little bit. But
>couldn't you play with the init parameteres DBWR_IO_SLAVES or
>DB_WRITER_PROCESSES to help improve write performance? I mean, I agree
>with
>Ross, there is only one disk, but maybe it could help a little to help
>simulate asynchronous I/O?
>Kev
>Just thinkin out loud again!
>
>-----Original Message-----
>Sent: Thursday, March 01, 2001 2:31 PM
>To: Multiple recipients of list ORACLE-L
>
>
>Actually, that message is invalid for Oracle8 DBs. From what I can gather,
>the DB_FILES init.ora parameter only
>potentially affected DBWR performance in Oracle7. In Oracle8, it ain't
>true.
>
>Remember, the DBWRs write dirty buffers (data in memory that has been
>modified from it's counterpart in a datafile) from the buffer cache
>(memory)
>to the datafiles (disk). In O7, the DBWR I/O clump size, or how many dirty
>blocks could be written at once (also sometimes referred to as the DBWR's
>"internal write batch size"), was calculated as:
>
> DB_FILE_SIMULTANEOUS_WRITES*DB_FILES/2.
>
>In O8, the DBWR I/O clump size is static, and is different from platform to
>platform. Thus, for Oracle8, the advise to change DB_FILES is bogus.
>
>HTH!
>
>Rich Jesse System/Database Administrator
>Rich.Jesse_at_qtiworld.com Quad/Tech International, Sussex, WI USA
>
>Disclaimer: After taking the Oracle8 Perf Tuning class, I think I know
>more
>than I do. Don't blame me for your (in)actions based on my opinion!
>
>-----Original Message-----
>Sent: Thursday, March 01, 2001 12:27
>To: Multiple recipients of list ORACLE-L
>
>
>not a dbwriter problem.
>on a "single-disk wonder", your best
>bet is to DUMP all indexes on loadable
>tables, then load your data, then rebuild
>the indexes.
>of course, that might take just as long.
>any possiblity of getting more disk?
>like, several? a raid controller?
>mit gluck!
>
>
>
>-----Original Message-----
>Sent: Thursday, March 01, 2001 11:26 AM
>To: Multiple recipients of list ORACLE-L
>
>
>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.

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Author: Reardon, Bruce (CALBBAY)
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