Hello Bob,

> collection (-g), probably to speed up the backup process. This led to
> a gap between OAT and OIT that was just huge.

The reason why you had big gap between OIT and OAT transaction markers is the absence of sweep.

> I successfully ran gbak with garbage collection (that took 48 hours).
> However, the transaction stats on the database do not seem to have
> been cleared up:

Backup was not necessary, sweep would be enough.

> My understanding was that I do not need to run a manual sweep if I am
> running gbak each night (with garbage collection enabled, of course).
> The question is, do I need to run a sweep on this DB, or is there
> something else that is preventing the OIT from advancing?

Yes, you need to run sweep. We recommend to our customer run sweep after backup (with -g) every night.

Among other things, sweep is very useful to detect database corruptions.
For example, if sweep completed immediately after start (without any message, as usual), and transaction markers did not move after the first committed transaction, it can mean index problem.

You can refer to "Firebird's Big databases" for more details
http://www.slideshare.net/ibsurgeon/firebirds-big-databases-in-english


Also, we are interested to have statistics from this database. We offer you free license of IBTM tool (which is non-invasive Windows client application which logs transaction markers states and visualizes their progress with various hints) in exchange of 2 weeks statistics from your database.
Contact me directly (ak at ib-aid.com) if you interested.

Regards,
Alexey Kovyazin
IBSurgeon

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> The server has been rebooted a number of times since the database was
> last restored from a backup (which occurred more than a year ago). It
> is difficult to find a maintenance window with this size database to
> do a full backup/restore cycle, so I'm looking for any other
> alternative to keep this healthy.
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> Thank you for your advice,
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> Bob M..
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