Subject Re: [Firebird-Architect] Re: Future feature priorities
Author Jesper B. Kiær

Havening been a Notes/Domnio developer/administrator for over 10 years I
can not expres my fondness for replication high enough.

To simply a new Domino server to a cluster ...wupti ..the clustered
databases get replicated realtime. If a clustered server goes down it
..the databases just gets replicated when it gets back up and everything
is in sync.

As a database administrator this is really what you ove.

I love Firebird and to get some kind of simular replication features would
be fantastic! :-)

Until then I advise (Java) people to take a good look at C-JDBC -
Software Raid features for databases. I think their ideas are simply

link :

and this to learn more

Very interesting reading.

Thanks to everybody working on Firebird!

It is really great to see everybody striving for making a great database
system .. even better! :-)

Best Regards
Jesper B. Kiær wrote on 02-08-2005 18:06:12:

> t_j_haynes wrote:
> >Have to agree that trigger based replication is a lot more flexible -
> >but it's arguable that this very flexibility allows far more scope
> >for error.
> >
> >Setting up a shadow is really easy and it should be relatively simple
> >to allow it to shadow to an adjacent computer over a dedicated
> >gigabit network cable without trashing the shadow if the other
> >machine is unavailable for a few seconds or minutes.
> >
> >
> It's a lot more complicated than that. If the connection drops, there
> has to be a resynchronization mechanism to bring the shadow back in
> sync, meaning that state must preserved both on the shadow and primary
> systems as well as a mechanism for the shadow machine to identify
> itself. Keep in mind that if the the shadow machine crashed, it may be
> necessary to go back a repeat a sequence of pages to make sure every one

> gets copied. Clone a new copy is an alternative, but a little pricey on

> a hundred gig database.
> But it could be done, of course. But I don't see anybody jumping up and

> down to take this on, particularly since much of what shadows once did
> is now handled better by RAID.
> There is no question, however, that disaster recovery must be one of
> Firebird's highest priorities.
> >The nearest I have to a performance comparison is between shadow
> >mechanism and stnadards triggers. Daabase write time to a single
> >table rose ~30% with a shadow, and over 100% using a trigger to copy
> >changed records. It seems to stand to reason that the raw disk block
> >level version should be faster, but I haven't tried your idea of
> >taking the processing to an external process, so I'll have a look.
> >
> >
> There will always be a tradeoff between bandwidth and cpu. If you're
> doing replication over a gigabit ethernet, you don't care about
> bandwidth. If you're replicating over a modest speed line to machine in

> a bunker 40 miles aways (as one of my customers does), you do care about

> bandwidth.
> RAID is cheapest, shadows next, and replication the most expensive. You

> get what you paid for.
> >Still - guess I have to live with what's there!
> >
> >
> >
> Then you are definitely on the wrong list. The developer's list is for
> people who aren't content with what's there.
> --
> Jim Starkey
> Netfrastructure, Inc.
> 978 526-1376
> Yahoo! Groups Links

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