RE: I/O and db_file_multiblock_read_count
- From: "Matthew Zito" <mzito@xxxxxxxxxxx>
- To: <kevinc@xxxxxxxxxxxxx>, "oracle-l" <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 12 Dec 2006 12:39:36 -0500
/dev/null is hard, as some OS'es, solaris notably, do evil tricks with
certain utilities (like cat something to /dev/null - it returns
immediately). Not sure about dd
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Kevin Closson
Sent: Tuesday, December 12, 2006 12:35 PM
To: oracle-l
Subject: RE: I/O and db_file_multiblock_read_count
I would have never though a write to /dev/zero would work...I
learn something new every day.
Can you try this test writing to /dev/null?
________________________________
From: Jesse, Rich [mailto:Rich.Jesse@xxxxxx]
Sent: Tuesday, December 12, 2006 7:16 AM
To: kevinc@xxxxxxxxxxxxx; oracle-l
Subject: RE: I/O and db_file_multiblock_read_count
I'm guessing that I'm limited by CPU on this IBM JS21
blade's LPAR (MPV, 2 cores max) with an SVC (virtualized SAN) backend.
topas showed kernel mode CPU >95% for most of the tests.
/oracle $ time dd if=S.dbf of=/dev/zero bs=1024k
16384+1 records in
16384+1 records out
real 1m3.044s
user 0m0.271s
sys 0m42.458s
/oracle $ time dd if=S.dbf of=/dev/zero bs=1024k
16384+1 records in
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