Re: asm on san

From: Michael Austin <>
Date: Thu, 11 Dec 2008 19:42:21 -0600
Message-ID: <ckj0l.10339$>

Palooka wrote:
> helter skelter wrote:

>> Hi,
>> I'm preparing to test some configurations on san storage array. I 
>> would like to find out what will be better in my environment: raid1+0 
>> or raid5. Other thing is what size of segment size should be 
>> configured on storage array. For example, I've got 5 disks in RAID5, 
>> so if ASM default stripe size for datafiles is 1MB, so segment size on 
>> strage shouls be 256KB to hit all drives, am I right?
>> What tools are You recommend to do tests like this: 
>> sequentail/sequence reads etc?  thanks
>> oracle 10gr2, rhel5

> I've found a lot of resistance to ASM from the *x admin and SAN folk.
> They don't seem to take kindly to Oracle and its DBAs invading what they
> see as their territory. Actually I have some sympathy with their
> viewpoint, if this is an enterprise class SAN, like EMC or something,
> and particularly where the SAN provider has a separate contract from the
> application/Oracle/*x admin providers.
> Test by all means, but my gut feeling says aim for RAID10. As others
> have pointed out, RAID5 tends to be sub-optimal, and not worth the cost
> saving, unless there is an exceptionally heavy preponderance of reads,
> as opposed to writes.
> Palooka

Living in an environment that requires very HIGH txn through-put on some servers and another several thousand database servers with multi-PB in storage - I can categorically say that you will NEVER see the difference on SAN between RAID5 LUN and RAID10 LUN or RAID6 LUN or .... whatever... Especially after adding the distributed and virtualized I/O capabilities in an ASM environment.

To counter your SA's objections, there is a VERY good book called "Oracle Automatic Storage Management Under-the-Hood & Practical Deployment Guide" written by Nitin Vengurlekar, Murali Vallath, and Rich Long with forward by Bill Bridge - the chief architect of ASM. In it, there is a chapter devoted to when the SA's "freak out".

This book also debunks a lot of myths associated with ASM - some that have been propagate in this and other forums.

It was in an e-book pdf form, but apparently has been removed due to copyright infringement. Received on Thu Dec 11 2008 - 19:42:21 CST

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