[dba-Tech] Performance in disc partitions

Erwin Craps - IT Helps Erwin.Craps at ithelps.eu
Mon Jan 28 04:18:01 CST 2008


The edge of the disk also means lower access times.
I don't know why because RPM is the same at the inner as outer side of
the disk.

I know that CD drives change their RPM speed depending how far they are
on the inner and outer side of a cd so the laser can keep up reading the
data, don't know if that is true for HD.
That could be an explanation for lower access times, because it takes
longer for the data to pass the head.


You can check http://www.hdtune.com/ it's a free disk performance check,
it will show you the transfer rate / access time for your disk over the
whole disk.

Erwin




-----Original Message-----
From: dba-tech-bounces at databaseadvisors.com
[mailto:dba-tech-bounces at databaseadvisors.com] On Behalf Of DJK(John)
Robinson
Sent: Monday, January 28, 2008 10:34 AM
To: 'Discussion of Hardware and Software issues'
Subject: Re: [dba-Tech] Performance in disc partitions

Thanks, John.  That would suggest higher transfer rates nearer the edge,
with some cylinders holding more than others.

Has anyone got any good links to this sort of stuff?

Oh, and of course I'm still interested in knowing whether the 'first'
partition is nearer the edge or the spindle...

John


-----Original Message-----
From: dba-tech-bounces at databaseadvisors.com
[mailto:dba-tech-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: 28 January 2008 00:57
To: 'Discussion of Hardware and Software issues'
Subject: Re: [dba-Tech] Performance in disc partitions


IIRC, the disk controller speeds up the writes as the tracks move
outwards
towards the edge of the platter.  IOW there is more surface area on the
outer tracks so they just bump up the waveform to allow more data to be
written in that larger surface area.  When thought of from that
perspective,
the outer tracks hold more data / track and so may require less head
movement. I have no idea whether the first volume is on the inner tracks
or
the outer tracks.


John W. Colby
Colby Consulting
www.ColbyConsulting.com 
-----Original Message-----
From: dba-tech-bounces at databaseadvisors.com
[mailto:dba-tech-bounces at databaseadvisors.com] On Behalf Of DJK(John)
Robinson
Sent: Sunday, January 27, 2008 7:47 PM
To: 'Discussion of Hardware and Software issues'
Subject: [dba-Tech] Performance in disc partitions

I am about to partition a new disc.  One partition will be very active
in
terms of reads and writes, another almost dormant.

Is there any advantage in performance terms in having the active
partition
as the 'first' one on the disc?  Or the last one?

It's a long time since I was involved in disc layout at a low level, and
I'm
wondering whether 'cylinders' these days are still all the same size,
with
the data near the edge of the platter just more spread out than that
near
the spindle - or not?

TIA
John


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