but how you do to run gfix -v -f in a deployement server ? because when the database is online (ie other client connected to it) i always receive :
bad parameters on attach or create database
-secondary server attachments cannot validate databases


so it's mean that we need to shuntdown the database ? right ?

stephane

--- In firebird-support@yahoogroups.com, "Ann W. Harrison" <aharrison@...> wrote:
>
> hvlad wrote:
> >>> I recommend to run gfix -v -full every day (night) when (if) it is possible.
> >> Hi Vlad,
> >> I'm just wondering... is it a good pratice to run gfix -v -full in a deployed database every day (night)? Or this recomendation is just for special cases like this of Stephen?
> >
> > I always recommend to validate database after any suspicious action (such as not correct Firebird shutdown or power failure etc) and, when possible, dayly (nightly). It is not always possible, i know.
>
> That's good advice as long as you don't take the results of the
> validation too seriously and rebuild a database that's functionally
> OK. Validation doesn't distinguish well between errors that are
> not corruption like orphan pages or orphan record versions and those
> that are serious.
>
> In Stephane's case, for example, if he killed a server that was
> hanging, he's likely to see orphan pages and record versions and
> possibly some bad pointer in the index.
>
> Firebird uses careful write rather than a write-ahead log, so
> each page change is written in only one place. The database
> also serves as its own undo log. Careful write is a simple
> concept - you write the thing before you write the pointer
> to the thing and you remove the pointer before you remove
> the thing it points to.
>
> What this means in practice is that when creating a back version
> of a record, you first create the back version, then change the
> new record to point to the back version, then change the page
> index to point to the new record. If the server crashes between
> any of those steps, you have an orphaned record version, but
> it was created by a transaction that failed, so nobody cares.
> Similarly, if you want to release a data page, you first
> remove it from the pointer page, then change the page inventory
> to say it's free. If you crash between those steps, the
> page inventory says the page is in use, but nobody is actually
> using it.
>
> If you validate that database, you'll get errors, but they're
> just wasted space, not actual corruption.
>
>
> Cheers,
>
> Ann
>