> On Aug 19, 2015, at 5:49 PM, tvd...@ymail.com [firebird-support] > <firebird-support@yahoogroups.com> wrote: > > I believe it is generally safe to have multiple simultaneously running > instances of Gbak backing up the same server, when all of them read data from > within their own transaction.
Right. Gbak is just another application. It generates its own BLR, which is unusual, but actually easier than generating SQL, if you happen to be a program. If it were a modern program, it would generate dynamic SQL. It's also pretty smart about dependencies between system table elements. However, there is not magic. A Gbak backup is just a read-only application, like any other. > Is that any different when Gbak is not supplied with the argument to skip > garbage collection? All applications that read the database do garbage collection by default. Coopertive garbage collection and the garbage collect thread all work together all the time. > Does that put either the backup file or (worse) the database itself at risk > of corruption? Perhaps someone can explain how this would work out under the > hood. No magic, except the normal magic of MVCC. My question to you is why run multiple simultaneous backups? Good luck, Ann > >
