RE: San & single point of failure

From: QuijadaReina, Julio C <>
Date: Thu, 20 Nov 2008 09:59:56 -0500
Message-ID: <>

Valid points! My point was that many storage admins go ahead with configuring storage without checking the implications of said configuration on the applications that will use that storage.


From: [] On Behalf Of Mark Brinsmead Sent: Tuesday, November 18, 2008 9:30 PM To: QuijadaReina, Julio C
Cc:;; oracle_l Subject: Re: San & single point of failure

What? Why beware of that? In some places I have been, this might be the good stuff! :-) (And yes, I do subscribe to BAARF.)

What you really need to worry about is the situation where some idiot gives you a RAID-1 where the two mirrored volumes are at either end of the same disk! Not only is there no protection, but the performance is the stuff of nightmares.

Sadly, many RAID vendors actually claim that RAID-5 (well, their RAID-5, anyway) is just as good as RAID-1. Or better. And many storage administrators will believe them. Often there is nothing you can do about this.

Happily, I have yet to encounter a storage vendor who claims that it is a good idea to do RAID-1 with two slices of the same physical device. But every now and again, you may see a storage administrator do it. Usually by accident, I hope. Thankfully, I have never encountered this one first hand, but I've seen close. :-)

On Tue, Nov 18, 2008 at 9:10 AM, QuijadaReina, Julio C <> wrote: Beware also of SAN administrators who setup RAID 5 and later give that storage to DBA's for their databases. It does not hurt to double check what kind of underlying RAID they've got for you.




-- Mark Brinsmead

  Senior DBA,
  The Pythian Group
-- Received on Thu Nov 20 2008 - 08:59:56 CST

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