Alan McDonald wrote:

>>There are several answers to this. The first is probably the obvious -
>>if the data is critical, the the machine it is running on would be using
>>a RAID disk, so allowing 'hot' handling of live data. The second option
>>is 'replication', where there is more than one set of hardware, each
>>maintaining a live copy of the data.
>>
>>Firebird supports an internal SHADOW facility which will allow it to
>>maintain two local copies of the data, and the second copy can be
>>accessed should the first become corrupt. This should be viewed as a
>>secondary method of 'backup', depending on the level of availability
>>required.
>
> Lester - I think this is misleading. Shadows are only good when there has
> been a hardware failure on one disk. In the event of corruption on one copy,
> the shadow mechanism is MOST likely to provide two databases with corruption
> since it is mirroring the disk writes to two places.
> Alan

That is why I said it was secondary. I think Jim put it in at a time
when RAID and things like that were not even thought of :) 30Mb of DISK
space was a luxury ;) so the alternative hardware solutions available
today should be checked out first. And THAT is independent of the
database engine.

--
Lester Caine
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L.S.Caine Electronic Services