Re: Laying out Oracle on a SAN

From: Thomas Roach <>
Date: Sat, 6 Feb 2010 19:24:46 -0500
Message-ID: <>

All a matter of preference really. If something like NFS or file system, then it might be a good idea to separate them into different mount points for manageability. With 10g and up I make use of the Flash Recovery Area and store my archivelogs there and I have DG so I don't multiplex the archive logs on my primary, but multiplexing is a good practice. If these are LUNS (block devices) I prefer to use ASM with 10g and up since it stripes the data across all disks within a disk group and that separates the I/O really well. At my new place, once we went to ASM with uniform block devices (they were different sizes before) we have the SAN lighting up like a Christmas tree and I/O performance is great. The issue with ASM is only Oracle knows about the disk location, but with 11g they now have the ASM file system or Database File System. I haven't had a chance to play with it but plan on it within the next few weeks.

BTW at my previous place, we did a POC with Oracle on an IBM z10 Mainframe running under zlinux and a DS8300 IBM San (supposed to be their top of the line). Because of the way it was architected, I needed 2TB of storage and they only allocated disks in 3GB chunks to maximize I/O. I could have gotten a larger size disk, but then I would only get 1 I/O channel to the disk. They said it was something about the way Mainframe or "DASD" storage works and this would give us max throughput (They called it a "Mod-3"). We threw about 700 Luns into an ASM group and then hammered it. The Mainframe experts working with us said they had never seen an 8300 light up like that before. Every disk was being hit pretty evenly (ALL of them) I forget our throughput but it was saturating the I/O channels (4 of them). After 8 hours, everything slowed down. The SAN was shot. They had to call support and replace some components.

I'm an advocate for ASM. Haven't had any issues. If you want to take backups though, you need to use some SAN Mirroring or RMAN.

Hope this helps.


On Sat, Feb 6, 2010 at 1:25 AM, Douglas Cowles <> wrote:

> Looking for tips as to laying out an Oracle DB on a SAN. I assume you
> probably want the fastest I/O for the redo logs and temp?
> The SAN I am working with has LUNS are carved up out of 10 or so disks on
> RAID5. Does it matter if we put the archive logs and the datafiles on the
> same LUN? Are these kinds of questions better suited to the SAN expert?
> Assuming I can defer a lot to the SAN expert, what I/O requirements and
> path requirements should I provide them? Centralized storage is
> centralized storage so I'm not sure how to parse things out. I also
> realize a lot of this may depend on the kind of SAN and its particular
> characteristics, but are there generic rules that can be provided?
> Doug C

Thomas Roach

Received on Sat Feb 06 2010 - 18:24:46 CST

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