Re: Summary: Oracle and Disk Mirroring

In article <30fm40$9f0_at_search01.news.aol.com>, rcronau_at_aol.com (RCronau) writes:
> In article <1994Jul19.002644.10921_at_rossinc.com>, davidgi_at_rossinc.com
> (David J. Gimpelevich) writes:
>
> >Can any OS mirroring system handle raw partitions?
>
> I doubt it. I believe that the definition of a raw partition is that the
> OS file system is bypassed and Oracle manages the physical disk.
> Therefore, it seems by definition, that OS mirroring is unavailable.

I am no expert but you CAN have mirroring of raw partitions. Both pieces of your mirror must be raw or both cook filesystem. Not a mix of both.

> >sudden power failure during a write
>
> My guess is that the data would be corrupted on both disks. Mirroring
> would not provide data recovery capability since power has been lost to
> the entire system.

I wouldn't use the term corrupted but rather inconsistant. To my knowledge there are no known utilities to check a raw partition for consistency or bad blockd except for 'dd'.

If this raw partition was an Oracle datafile, then your database will carry out the roll forward/rollback recovery because a write is not buffered and Oracle will know if the transactions were completed or not. Even with async I/O, they will provide notification to Oracle to indicate if the write was successful or not.

My recommendation is that your archive logs be on cook filesystems.

hope that helps a bit

ta
tony

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