Re: 1M STRIPE SIZE BEST?

From: Thomas Day <tday6_at_csc.com>
Date: Thu, 21 Nov 2002 06:33:48 -0800
Message-ID: <F001.00508D80.20021121063348@fatcity.com>

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"                                                                                  
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                    Sent by: root        Subject:     1M STRIPE SIZE BEST?                                         
                                                                                                                   
                                                                                                                   
                    11/20/2002                                                                                     
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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

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Received on Thu Nov 21 2002 - 08:33:48 CST