RE: redo log file setup with mirrored drives

On Tue, 2002-11-26 at 10:50, Stephen Lee wrote:  

 And from another post ...
> > Because my OS/hardware IS reliable a corrupted
> > log file that is mirrored outside of Oracle will be corrupt -
> > the original is corrupt, so is the mirror.
>
> In one sentence you have claimed that your "OS/hardware IS reliable" and
> talk about it corrupting log files. Are we having a problem with the
> definition of "reliable" here?
>

Hmmm..I don't think the original poster is saying the OS corrupted the log file. The post is merely mentioning that if a non-oracle mirrored redo log was to become corrupted(by any means) the mirror copy will be corrupted as well, but an Oracle multiplexed copy might not be.

> This goes back to an old post of using NT versus Unix. If you recall, my
> reply was that security on NT was so bad, that it is not a good choice.
> This stems primarily from the fact that NT is essentially a single-user OS,
> built around the administrator, with some multi-user extensions kludged on
> to support non-administrator pseudo-users.

> Going back to the original post on this topic: There was nothing that
> suggested they were in a pathological environment. For what it's worth,
> when we had databases on NT, we followed a strict directory naming routine
> and made it clear to the NT admins that any directory with certain names
> were not to be touched. If anything needed to be done with those
> directories, they were to page us.

Last time I checked most SA's have root access. Therefore they can delete(accidentally or otherwise) any of your Oracle files. Granted, Joe Schmoe user won't be able to do this, but how often is user Joe Schmoe logging on to an NT Oracle box? So I would say your NT point is moot. The same security precautions from admins is needed in a Unix environment as well.

If you read the original post again, the poster asked if there was any "danger" to just using OS mirroring. I think the potential dangers were addressed and the question was answered. I don't think anyone was questioning the reliability of OS mirroring, but as an administrator, I think it is in my best interest to take worst case scenarios into account.

> Concluding remarks:
> While the scenarios of gloom and doom that have been painted by some seem to
> be credible, I've have yet to witness, in my years of personal experience as
> a sys admin and a database admin the unreliability that some claim to exist.
> That being the case, I must go with the arrangement that I think offers
> fault tolerance with the best performance.

As with any database installation the old "it depends" works every time. There are best practices, but each situation is different and has different requirements for reliability, uptime,security, etc. If just using OS mirroring is the best choice for your installation that's great, but it might not be the best choice for all.

-Brian

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Author: Brian Haas
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