Subject Re: [ib-support] Problem in backing up
Author Ann W. Harrison
At 01:31 PM 1/6/2003 +0100, Pete Clark wrote:

>Surely there should be a full stop, as in
>-secondary server attachments. Cannot validate databases
>I thought that it meant
>"The secondary server attachments are not able to validate the database"
>which made no sense at all to me...

Not all programmers are great masters of the English language
(or any other humanly comprehensible language). What was in
the mind of the writer, I think, is that yours is a secondary
attachment. Since all of us consider ourselves primary,
confusion is rampant.

>I just hope that this is what I should be doing - remember, the
>original problem was that I could not back up the database.

Did you happen to notice if there were any error messages, either
from gbak or in the server log?

>I would love to understand about how the database can function when
>apparently faulty - I would guess that the database would slow down a
>lot when working with a faulty structure.

No, not usually. There are lots of different ways that the
database can be corrupted - most of them make no difference
unless you touch the bad page, at which point the error goes
from benign to catastrophic. That's why things like sweep
and backup tend to get these errors - they read all the data.
However, they won't find bad index pages since neither reads
indexes on user data.

> I would also guess that one
>or more records could be lost. Is that correct?

If an index is corrupt, then no data is lost, though trying
to fix the problem can easily cause data loss. You'll tend
to lose a whole page of records if you lose any. With worse
luck, you can lose a whole set of pages of data. Worse luck
still can leave you with nothing you can see at all, even
though all the data is actually there. Happily, both the
IBSurgeon guys and I can usually get data back - oddly enough
a single page of lost data is harder to get than a whole database.

>Loss of data is not important to me,

Loss of data is extremely important to me, so do let us know
what you find out.


We have answers.