Mogens,
In regard to the number of spindles issue: James Morle has some excellent discussion on that in 'Scaling Oracle 8i'. ( I think it's that book ) When some of the newer larges drives are used in a given configuration, they mabe be able to outperform older drives in a similar configuration with a larger number of spindles. I say 'older' since smaller drives usually aren't using the latest technology and the newer ones have sufficiently higher throughput to match the capability of a larger number of drives in given configuration. Food for thought, anyway. Jared On Sunday 20 January 2002 06:50, Mogens N�rgaard wrote: > Diego, > > I agree with you 100% and didn't express myself correctly in my email. > The more spindles the better. What I meant to say was that you must > never buy disks by taking your total needed amount of space and divide > by the number of big disks you can get hold on :). It's the number of > IO's required by the disk system that matters, not the size... > > Thanks for making this clear to everyone. > > Mogens > > Diego Cutrone wrote: > >Mogens: > > Just let me disagree with you at only one point. According to my > >experience, I think that the size of the disks in an array does matter > >sometimes. It's not the same to have 24 9GB disks that to have only 3 of > >73GB. You have 24 spindles againts 3, the first option (in a well > > configured system of course) will give you better performance in > > enviroments where you have a lot of concurrency and many users. > > However I think that what I've written above might not be correct (may > >be it should be tested) if the 73GB outstands for a long way the 9GB disks > >in terms of seek time and transfer rate. > > Take a look at an extract of Gaja's paper "Implementing RAID on > > Oracle": > > > >"5) Procure the smallest drive money can buy, keeping in mind scalability, > >limits of the host > >machine, the disk array and growth projections for the database. This is a > >tough one these > >days, with 18 GB drives considered as small drives. > > > >6) Bigger and faster drives are not always better than smaller slower > >drives, as the seek times > >for larger and faster drives with larger form factors, may be more than > >their smaller and > >slower counterparts. This is not that big of an issue, if your drives > >support a built-in track > >buffer cache for storing an entire track's worth of data from read > >request(s)." > > > > > >HTH > >Greeting > >Diego Cutrone > > > >----- Original Message ----- > >To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > >Sent: Tuesday, January 15, 2002 10:25 PM > > > >>Jon, > >> > >>It's one of those "how many bags will I need in the supermarket?" > >>questions - it depends. > >> > >>Consider: > >> > >>- RAID 1+0 is much better than 0+1. > >>- Three disks is not much w.r.t. IO capability. If you have three > >>concurrent users you'll be OK :) > >>- Size doesn't matter (who cares if it's 10, 36 or 73 Gig disks? It's > >>the IO capabilitity that counts) > >>- I'm new to this list, so I don't know if this will work, but I've > >>attached a brilliant presentation by our old friend James Morle (check > >>out www.ScaleAbilities.com) regarding SAN, NAS and RAS (Random Acronym > >>Seminar). > >>- If you're only striping across three disks (is that really a SAN?) > >>just SAME (Stripe And Mirror Everything). It might not be good, but it's > >>simple. > >> > >>Jon Behnke wrote: > >>>We are in the process of setting up a SAN using RAID 0+1 for our > > > >database. > > > >>>In our current environment, we are able to separate our tables, indexes, > >>>rollback segments, and archive logs on different disks. On the SAN we > > > >would > > > >>>have six 73 gig disks on RAID 0+1 for a total of about 210 Gig of usable > >>>space (3 disks worth of space). > >>> > >>>Some white papers that I have read suggest attempting to separate the > > > >data, > > > >>>indexes, and rollback segments on separate RAID volumes, and others > > > >simply > > > >>>suggest that the performance boost of striping will supercede the > > > >separation > > > >>>of these items. > >>> > >>>Can anyone offer any comments or suggestions? > >>> > >>>Jon Behnke > >>>Applications Development Manager > >>>Industrial Electric Wire & Cable > >>>Phone (262) 957-1147 Fax (262) 957-1647 > >>>[EMAIL PROTECTED] ---------------------------------------- Content-Type: text/html; charset="us-ascii"; name="Attachment: 1" Content-Transfer-Encoding: 7bit Content-Description: ---------------------------------------- -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Jared Still INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). 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