DJK(John) Robinson
djkr at msn.com
Mon Jan 28 06:01:08 CST 2008
Well, *IF* the outer track holds more than the inner track, then you get more data passing the head in one revolution, giving higher transfer rate and fewer seeks - so lower access times overall. But there's still that *IF*. CDs are different, of course, with their variable speeds. John -----Original Message----- From: dba-tech-bounces at databaseadvisors.com [mailto:dba-tech-bounces at databaseadvisors.com] On Behalf Of Erwin Craps - IT Helps Sent: 28 January 2008 10:18 To: Discussion of Hardware and Software issues Subject: Re: [dba-Tech] Performance in disc partitions 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 _______________________________________________ dba-Tech mailing list dba-Tech at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-tech Website: http://www.databaseadvisors.com _______________________________________________ dba-Tech mailing list dba-Tech at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-tech Website: http://www.databaseadvisors.com _______________________________________________ dba-Tech mailing list dba-Tech at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-tech Website: http://www.databaseadvisors.com _______________________________________________ dba-Tech mailing list dba-Tech at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-tech Website: http://www.databaseadvisors.com