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Re: Do Disk Heads Stay in the Begining or Middle of a disk when idle ?

From: Stephan Bressler <stephan.bressler_at_siemens.com>
Date: Thu, 4 Jul 2002 16:18:57 +0200
Message-ID: <ag1lgk$is2$1@news.mch.sbs.de>


Hi,
one reason might be that "the beginning of a disk" resides on the edge of the disk (not in the middle, sorry for that expression). Using ZoneBitRecording, more sectors per track are stored there. So more data can be written during a single rotation of the disk. The disk is faster on these tracks compared to tracks located near the spindle.

I don't think this will improve performance very much as long you use dedicated disks for redo log enabling sequential IO on these disks. Interleave them in order not to interfer with the archiver process (e.g. log 1+3 to disk1, log 2+4 to disk2).

Regards
Stephan

"Bass Chorng" <bchorng_at_yahoo.com> wrote in message news:bd9a9a76.0207031453.3d32bf84_at_posting.google.com...
> In ixroa Steve Adams' Disk Configuration for Online Redo Logs, he stated
> that log files should be located in the begining of a disk to minimize
> disk arm movement.
>
> In IBM's Shark documentation, it states that log files should be located
> in the middle of a disk to minimize access time.
>
> Years ago, I remember Informix DBA guide stated that the physical logs
> ( = rollback segments) and logical logs ( = redo) should be located in the
> middle of a disk because disk heads hover above the middle section of
> a disk once it is powered on.
>
> Does anybody know which is right ? Or does it depend on the disk
manufacturer
> ( I really doubt that though ) ?
Received on Thu Jul 04 2002 - 09:18:57 CDT

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