> You must remember, we use FreeBSD...We can take a filesystem snapshot,

and spend as much time as we like doing a filesystem copy

If you are running LVM under Linux, then you can take snapshots of the
file system.

-----Original Message-----
From: firebird-support@yahoogroups.com
[mailto:firebird-support@yahoogroups.com] On Behalf Of Nigel Weeks
Sent: Monday, May 07, 2007 12:45 AM
To: firebird-support@yahoogroups.com
Subject: RE: [firebird-support] Database for images

> I think it's the first time i heard about someone using rsync to
> synchronize firebird databases. I would like to know more about your
> experience.

> - Did you measure if rsync is efficient to make its job in this case?
> I don't know FB internals, but after some thousands of transactions,
> is the database file in a state rsync can track its similarities and
> still optimize the transfers?

When it comes to keeping two files on different hosts, rsync absolutely
files.
As you may know, it only copies the deltas (the changes) over the wire,
so if you've got a 30GB .fdb file, and you add one record, the only data
it will move over the wire are the parts of the file containing the new
record, and updated indexes, and any pages marked as bad/old/available
for re-use.

The ins and outs of it are outside the scope of this email, but
basically, it ensures the checksums of the file are identical - an exact
mirror image.

> - Do you really do this on live databases? Never had problems? Maybe
> if i lock the database (as if i would make a file copy) i could use
> this approach on windows/linux.

You must remember, we use FreeBSD - a very different beast to Windows
and Linux. We can take a filesystem snapshot, and spend as much time as
we like doing a filesystem copy of the .fdb from the server to anywhere,
and Firebird can happily continue on it's version of the filesystem.

Rsync simply enables us to drastically reduce the amount of data we need
to move across the network to the DR servers.

> - Is there someone doing this?

I doubt many people are. Most people think Linux and Windows are the
best choices available...

Regards,

Fabiano.




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