Oracle-L: RE: sequential reads/scattered reads

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Thu, 11 Jul 2002 05:53:22 -0800
Message-ID: <F001.00494C7A.20020711055322@fatcity.com>

Moving stuff around won't reduce I/O traffic, it'll just spread it around across different devices.

Don't focus on how much I/O your system does, focus on how much *time* an important process spends *doing* I/O. It's Amdahl's Law: If you improve I/O latencies by 50%, but your program spends only 2% of its response time doing I/O, then your program's response time will improve by only 1%.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com

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-----Original Message-----
oraora
Sent: Thursday, July 11, 2002 6:33 AM
To: Multiple recipients of list ORACLE-L

Guys,

Querying my v$session_wait shows 10 rows each DB FILE SEQUENTIAL READ and DB FILE SCATTERED READ.

manuals explain it all b'coz of I/O.

there are 33 tables and 110 indexes in the same USERS tablespace with only one datafile USERS01.DAT of size 12GB.

it's physically laid out in D:\oracle\data. but the hard disk capacity is 100GB with 8 disk heads and RAID5.

will not moving the tables and indexes to seperate tablespace reduce I/O traffic ? my manager here says that since it is configured with RAID5 and 8 disk heads , it's not a problem.

is it so ? is he right ?
plz. clarify me. i need to explain him.
it's urgent.he is sitting on my head.

TIA.

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Author: Cary Millsap
INET: cary.millsap_at_hotsos.com

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