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
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