You're most likely seeing the effects of caching here. The database
you're using will probably store updates in cache and will write all the
changes to disk on it's own time cycle. Even at that point, the
operating system will maintain it's own filesystem cache and won't
actually send the writes to the hard disks until it makes sense to do
so.

The reason the operating system and database use write caching is to
limit the amount of expensive small write operations on your disks. If
your database wrote every new row to the disk immediately after it
receives each new row, you'd end up with 1000's of small writes per
second on large databases. This is extremely inefficient and bad for
performance when compared to say writing 1000 rows at a time in a big
contiguous chunk (page).

If you'd like to help prevent this occurring again in the future, maybe
you can look into database replication? I'm not too familiar with
replication, but I would assume that if the machine goes down after
sending an email (but before the local database write is complete) then
the replication slaves would also have received the new data via the
network?

As Glenn said, this is quite complex!

Regards,

David


On Fri, 2009-07-24 at 04:41 -0700, Jon Hardcastle wrote:
> We had an issue with our Mantis machine going down, and in the midst of it 
> all someone raised an issue - the email was dispatched but there is no trace 
> whatsoever of the issue? infact the issue number is in use by another issue 
> that is completely unrelated?
> 
> Does anyone have any idea how that can happen? Surely the email but be AFTER 
> the point that the bug record was/is created and hence the bug id is 'bagged'?
> 
> -----------------------
> N: Jon Hardcastle
> E: [email protected]
> 'Do not worry about tomorrow, for tomorrow will bring worries of its own.'
> -----------------------
> 
> 
>       
> 
> ------------------------------------------------------------------------------
> _______________________________________________
> mantisbt-help mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/mantisbt-help

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