[rescue] Mounting and Dumping

[Mike Meredith]

On Wed, 14 Jan 2004 14:04:39 -0500, Sheldon T. Hall wrote:
> Janet L. Campbell writes ...
> > On Tue, 13 Jan 2004, Sheldon T. Hall wrote:
> > > So ... in reading the ufsdump doco for Solaris 7, it really
> >
> > 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.
> 
> Inconsistent, I can stand,  Unreadable, I can't.  Will the fs activity
> while dumping a mounted filesystem make the dump unusable, or just

If you find a reliable answer, I'd be very interested in hearing about
it. I wouldn't use ufsdump myself despite ufsrestore having one of the
nicest interfaces for emergency restored I've seen.

A few years ago I was converting work's backup script from Digital Unix
to Solaris and spent a long time looking into ufsdump. At the time I
couldn't find a definitive answer to this problem. I seem to recall
someone commenting that a write to a filesystem that is being dumped can
cause the entire dump to be useless if you're unlucky.

I don't like relying on my luck when it comes to backups.

http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/71515
http://sunsolve.sun.com/pub-cgi/retrieve.pl?doc=fsrdb/70105
http://www.sunmanagers.org/pipermail/sunmanagers/2001-January/000915.html
 (Read all the way through all the responses to that one)

Of course using fssnap is a whole different ball game.

Yes I know I'm not in agreement with the majority view here which means
I'm probably wrong :)

> > 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.
> 
> Jochen Kunz suggests the same thing: the Classic isn't as fast at the
> tape. He also suggested disableing compression to help it stream, and
> I'll try that.

Disabling compression on the DLT drive or the Classic ? The DLT drive
should be able to stream with it's compression on. Not streaming is
(long term) a recipe for dead tapes and drives.