RE: 9i-OCP Question

From: Boivin, Patrice J <BoivinP_at_mar.dfo-mpo.gc.ca>
Date: Thu, 31 Jul 2003 03:59:29 -0800
Message-ID: <F001.005C7F7A.20030731035929@fatcity.com>

We use a SAN.

Where does that leave me?

: )

Patrice.

-----Original Message-----
Sent: Wednesday, July 30, 2003 7:10 PM
To: Multiple recipients of list ORACLE-L

I'm constantly amazed (and relieved!) that there's disagreement on the most fundamental principles.

First, I found myself nodding at Roy's first post. On some databases, I have three log groups, with two members each. Each set of members has its own disk. I'll concede the argument that the instance goes down right away if one of the drives fails, but I _still_ have a full set of logs on the other drive, and that's a good thing, right?

Second, if I have three groups of two members each and follow what seems to be the consensus opinion, I have three drives, each holding two members, one from each group. In this case, aren't the two members on the same drive identical? If I lose that drive, I lose that entire log group, and therefore no longer have a full set of logs--so what's the point of having two copies? I also lose the instance immediately if that group happens to be the current group at the time of disk failure.

Third, while I agree that every member of every group should ideally have its own disk, does ANYONE actually configure their DB this way? I had a hard enough time dedicating one or two disks to redo logs; who can dedicate eight, especially given drive sizes of 72+ GB and (single) log file sizes of, what, 100 MB?

• "Pardee, Roy E" <roy.e.pardee_at_lmco.com> wrote:
  > Yep, that's right--I had it wrong. You need to have at least one
  > member from each group in order to do a full recovery. I see now
  > from my trusty dba fundamentals I class text that each member of a
  > group is identical (or is supposed to be).
  >
  > So I guess I'll go back to being confused about why the answer to the
  > question below is 2. I guess 2 is the minimum required to survive a
  > single disk failure?
  >
  > Cheers,
  >
  > -Roy
  >
  > Roy Pardee
  > Programmer/Analyst/DBA
  > SWFPAC Lockheed Martin IT
  > Extension 8487
  

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Author: Boivin, Patrice J
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Received on Thu Jul 31 2003 - 06:59:29 CDT