[rescue] Mounting and Dumping

[Janet L. Campbell]

On Tue, 13 Jan 2004, Sheldon T. Hall wrote:

> So ... in reading the ufsdump doco for Solaris 7, it really emphasizes the
> need to dump only UNmounted filesystems.  So my questions are ...
> 
> 1)  Is that really neccessary?

It depends on what's happening to the filesystems at the time.  The 
principle danger of dumping a mounted filesystem is that writes may make 
the dump inconsistent.  This is *usually* not a big problem when the 
machine is otherwise quiet.

> 2)  If so, can I unmount, dump, and re-mount filesystems under script/batch
> control?

If you could interactively, sure.  It's probably overkill, though.

> 3)  All of 'em?  If I unmount /usr or /, how do I run the program?

With difficulty.  It's really not necessary to quiesce write access as
long as you don't really care about the writing that is in progress during
the dump.

> 4)  What's a fellow to do?

Well, fssnap is quite nifty.  It solves this problem nicely.

> I have separate filesystems for /, /usr, /var, /users (everyone's home
> directory), etc., but they are all on one disk.  In running a test, it
> sounded like the Classic wasn't keeping up with the DLT drive.  Would
> putting the DLT on the the SunSwift card's SCSI bus help that?

Maybe.  If you're dumping a partition with lots of small files, the 
Classic may just not be able to keep up with the DLT drive because of 
disk speed and fragmentation.

If you have a bunch of scratch space, you can use this to "stage" dumps by 
dumping to this space and then dd'ing off to tape.  Some backup suites, 
such as Amanda, do something similar.

-Janet