Maybe I've forgotten something fundamental about the way RAID 5 works, I dunno.
But I'm having a hard time understanding how stripe size is going to determine the number of heads used in an IO. RAID 5 distributes the data across all spindles, with 1 or more of the spindles for any IO being used for the parity data. Someone care to enlighten me? Thanks, Jared On Thursday 21 November 2002 06:33, Thomas Day wrote: > We had a discussion about a year ago here and if I remember correctly the > "best" stripe size is a function of number of concurrent users. With a > small number of users you want a small stripe size so that each read i/o > will utilize the maximum number of heads. It will also tie up the RAID > device for the duration of the read. With a large number of users you want > a very large stripe size so that a minimum of heads will be used for each > read and the RAID device can handle multiple requests at a time. > > I don't recall any specific numbers and, as you say, the technology is > changing so quickly that a discussion from a year ago may not be pertinent > to today's environment. > > > > > "Post, Ethan" > <Ethan.Post To: Multiple recipients of > list ORACLE-L <[EMAIL PROTECTED]> @ps.net> cc: > Sent by: root Subject: 1M STRIPE SIZE BEST? > > > 11/20/2002 > 05:53 PM > Please > respond to > ORACLE-L > > > > > > > A number of papers recommend a stripe size of 1 M (even for EMC) for > volumes > containing data files. I also have the following email from Eyal Aronoff > of > Quest dated Nov 2000. A number of the white papers are more recent. > > ============================================================ > The reasons for a larger stripe size on a non-RAID 5 device are: > 1) Sequential reads are faster if you can take advantege of the read ahead > built into the disk caching > 2) If a 64K read does not start on the first block of the stripe, two > "spindled" are locked for the duration of the read > > However, lately we have been testing some EMC gear and it looks like EMC > have optimized both of those for smaller strip size too. > > The bottom line - I no longer have an opinion one way or another. The > undelying technology just changes too rapidly. > > Eyal > ============================================================ > > Your opinions/comments as far as a "best" practice in setting stripe sizes > would be greatly appreciated. > > Thanks, > Ethan > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Post, Ethan > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > 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). You may > also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Jared Still INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- 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). You may also send the HELP command for other information (like subscribing).
