Mario wrote:

> In this relatively un-edited database, it appears to be no reason for
> running the backup with Garbage collection option turned on ?

Exactly. I suppose your sweep interval is set to some reasonable value,
so it will do housecleaning when needed. There is IMHO no need to put
that burden on backup process.

> Interestingly, the original 22 MB file was compressed to only ~4.5 MB
> in the output.gbk. After restoring, the gdb file is now only 9.7 MB in
> size - less than half of the original size. Is that normal, expected ?

It is. The reason is that Firebird does not return the "extra" space to
filesystem, but keeps it for reuse. The reason is that it is much faster
to use already allocated space, than ask for new. There are even some
people on this list who deliberately make their db grow upon creation,
and create a lot of reusable space. All in order to get better performance.

> BTW: what is the function of the option: "Create Shadow Files" in the
> restore ?

If you turn it on it will create shadow copy of database. You can read
in docs about shadows, here a short copy/paste from ibphoenix.con website:

A database shadow functions as an exact duplicate of the original
database, maintained in real time by the InterBase server. If the
original database is lost through user error or a hardware problem, the
shadow can take over as the primary database.

A shadow runs automatically, with little or no maintenance. It can be
activated immediately if the original database is damaged, providing
valuable protection in addition to your regular backups. However, since
the shadow is a live, real time mirror, it cannot help you if the
original database is damaged by a user error. Shadows also impose a
small performance penalty, but this can be alleviated with more powerful
hardware.

--
Milan Babuskov
http://www.flamerobin.org