From: Andrew Mobbs <andrewm@chiark.greenend.org.uk>
Newsgroups: comp.sys.sun.hardware,comp.databases.oracle.server
Subject: Re: Question about Sun disk space configuration for large Oracle database
Date: 08 Aug 2001 09:21:08 +0100 (BST)
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Originator: andrewm@chiark.greenend.org.uk ([195.224.76.132])


Richard Piasecki <ogo@mailexcite.com> wrote:
>Greetings.
>
>I am currently developing the physical disk space layout for a large Oracle
>database (over 2 terabytes of disks), and I wish to solicit some opinions as
>to how to make this work. My configuration calls for each Oracle tablespace
>to be placed on separate RAID 0+1 arrays. Each RAID array would be
>controlled
>by its own RAID controller. There are 13 such arrays and the largest of
>these
>arrays needs to be at least 550 Gigs. The system administrator with whom I
>am working on this project has reviewed Sun hardware specs and has come to
>the conclusion that 13 RAID controllers is not do-able. Instead, he
>recommends using fewer RAID controllers and allowing each one to control
>multiple arrays. I am primarily concerned with reducing I/O contention for
>the Oracle tablespace files and wonder if a single RAID controller can
>handle
>multiple requests for different arrays in parallel. There is another problem
>in that, according to his analysis, each RAID 0+1 array can accomodate, at
>most, 8 disks. Assuming 36 gig disks, this would mean that the largest size
>of a single RAID 0+1 array would be 144 gigs (4x36), significantly less than
>my 550 gig target. Below, you will see my proposed physical layout for each
>partition and its use. My questions for the Sun/Oracle experts are as
>follows...
>
>1) If I allow a single RAID controller to handle multiple arrays, how can
>   I minimize I/O contention to those arrays. Can a single RAID controller
>   handle multiple requests to different arrays in parallel?
>2) How do I set up a partition of 550 gigabytes? Can a single array be
>   composed of 32 disks (assuming RAID 0+1 with 36 gig disks)?
>3) Specifically for the Oracle DBAs, would you recommend any changes to
>   the proposed configuration to improve performance?
>4) If you were in my shoes, how would you do it? What specific Sun hardware
>   should be used?

I'm currently seeing good performance from Sun T3 arrays (9 disks per
array IIRC), with the controllers handling hardware striping across the 9
disks, and Veritas handling combining 10 T3 arrays into a single RAID 1+0
stripe set.

I'm afraid I'm not involved enough in the hardware config to know what
the controller layout is.

I find SAME offers sufficient performance, with more flexibility than a
dedicated layout. However, I'm strongly in the camp that says keep your
redo seperate from the SAME stripe.

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/