[Dovecot] Questions about single intance storage

[Terry Carmen]

>> If we can not safely restore from backup a user's mailbox with SiS  
>> enabled, we can not enable SiS. Any plan to include this backup  
>> recovery tool in dovecot 2.0.X or 2.1?
>
> I'd first have to design it. And before designing it I'd need to  
> look into how the backup softwares usually work.. If anyone has any  
> ideas about this, I'd like to hear.

BackupPC uses rsync by default for *nix boxes.

No idea what SiS is, but I'm guessing you're running into the same  
problem as backing up any other open file with changing internal data  
that may be inconsistent.

This is exactly what it's difficult (and pointless) to backup an open  
MySQL database or a SQL Server database. The snapshot of what's in  
memory doesn't always match what's on disk.

The only ways I know around this are to periodically create a backup  
copy that *is* consistent and restorable and a utility to restore the  
backup back to the "live" storage format, or create a method for the  
software to flush it's buffers to disk then disconnect from the data  
file while the backup process is running.

The first option takes ~2x the storage space, while the second option  
makes the user's data inaccessible during the backup.

My apologies if I'm misunderstanding the problem and have been  
rambling for no purpose. 8-)

Terry