Re: Perfomance problem backupscript (more details and tests)

Les Mikesell <[email protected]> wrote:

> > Crossing mount points in backups is not something that I would call the right 
> > way to go.
>
> Depending on why the original died and what I wanted to have when I got
> done rebuilding, changing filesystem types and/or mount points might be
> a good thing.  Certainly the ability to make those decisions at restore
> time is a good thing. 

Well, you told me that you use Amanda. A decent Backup control system should
be able to be able to handle your problem together with a backup system.

-	The usual way for a backup is to backup whole filesystems.

	However, star allows you to backup _partial_ filesystems if you
	care about the constraints. The constraints are that (on a fully
	POSIX compliant system) no directory from outside the scoped area
	may be renamed _into_ the scoped area and (in case ctime is not
	following POSIX rules) no _file_ is moved from outside the scoped
	area _into_ the scoped area.

-	If you are talking about mount points inside a _logigal_ area, then
	any part of a directory tree that is below the mount point is
	a complete filesystem to backup.

-	If you like to restore a _logical_ file tree area into a single
	filesystem, you need a full backup from top level filesystem (in case
	that the logical tree is spanning the whole top level fs) or a
	partial backup from the directory of interest. In addition, you need
	full backups from all filesystems that are mounted below the top
	level directory of interest.

	You first restore the level 0 dump of the top level directory and
	all incrementals and then continue to do the same with the formerly
	mounted directories in an order that increases nesting level.

You are either a backup operator that knows what he is doing (and does the right
things by hand) or you use a decent backup control software.

BTW: The Amanda people did tell me that they would start to implement support
for star once incrementals are posssible. If you like to use amanda, how about
asking the amanda crew about a new version that supports star?

Jörg

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