Subject Re: [firebird-support] incremental backups, wenn the SQL Firebird is running
Author Helen Borrie
>Sean Leyne wrote:
>> But to come back to the original question, is there any danger of running a VSS database while Firebird database is running? Absolutely none!

At 11:28 AM 28/11/2010, Paul Vinkenoog wrote:

>But then I don't understand this, from the OP's question:
>> The manufacturer of my buckup software
>> <> told me, it is important,
>> that Firebird works with / supports the Microsoft VSS service
>This suggests that Firebird ought to recognize and/or cooperate with the VSS service, "or else".
>I don't know anything about VSS, but given the choice I'd definitely go for gbak or nbackup. They were designed to do exactly that job. They know what's going on *inside* a Firebird database - something that VSS probably isn't aware of.

Volume shadowing, that came in with WinXP/Server2003, *was* suspected to cause problems for Firebird, although different kinds of problems than its older alter ego, SystemRestore.

Quoting the subject of the original posting - "incremental backups, wenn the SQL Firebird is running", it sounds as though the OP thinks VSS provides an incremental backup capability. It doesn't. It makes a periodic read-only snapshot of the entire volume, at block level. Thus, if Something Nasty should happen to the volume, the *entire volume* would need to be restored and the image would be that taken at the last snapshot.

As far as I understand it, third-party backup software like Acronis (along with a heap of others) makes use of the snapshot volume copy by taking its own copy of the copy, extracting out blocks pertaining to a file and regrouping them readt for a restore operation to stitch them together in a manner analogous to disk defrag.

If that *is* as I understand it to be, then I cannot see how Firebird could be said to support the VSS, let alone "work with it". One would need to be at least *suspicious* that a Firebird database file restored that way would be thoroughly corrupted, since its inventory of block addresses is stored and mapped by indirection, within the database itself.

I was interested to see Sean commenting so definitively that it was safe. Sean, are you using it with your own Windows-based database volumes? Have you tried a restore?