RE: redo log file setup with mirrored drives

> -----Original Message-----
> We do redo log file multiplexing to protect against fat
> fingers and other odd-ball stuff that have caused problems
> for an entire file system. Call it an unreliable OS, poor SA
> (ok, maybe even DBA) practices

I do it because it's a CYA thing of doing it by the book. I've listened to a lot of debates about database things and been amazed at the reasoning behind why people do what they do. I've lost count of how many debates I've heard about extent sizes and numbers of extents, the majority of it pure superstition. In the end, no matter how scientific or superstitious the reasoning, CYA trumps all. So that's why I do it. But, in fact, this whole thing about corrupt blocks is flawed reasoning. If an OS cannot do disk writes in an absolutely reliable way, then the OS is unusable. The bad writes will occur throughout the system. This includes when your logs get archived and writes to data files. Put those two together and what do you get?

Actually, there is one advantage to hardware mirroring of archives. On Oracle duplexed archives, my experience is that it is inevitable that you will have one destination fill up while the other one doesn't. In which case Oracle quietly quits using the one destination even after the files are removed during a backup. I wrote a script to monitor when Oracle has stopped duplexing archived logs for those where we don't have hardware mirroring.

I was amazed at the non-security that seems to be rampant out there, with mischievous people running around deleting files. I kept reading about it and thinking you've got to be kidding.

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Author: Stephen Lee
  INET: slee_at_dollar.com

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