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From: asp@COS.COM (Andrew S. Partan)
Newsgroups: comp.unix.questions
Subject: Re: Restoring to a smaller fs?
Message-ID: <484@cos.COM>
Date: Wed, 21-Oct-87 14:18:27 EDT
Article-I.D.: cos.484
Posted: Wed Oct 21 14:18:27 1987
Date-Received: Sat, 24-Oct-87 04:19:52 EDT
References: <482@cos.COM>
Organization: Corporation for Open Systems, McLean, VA
Lines: 45
Keywords: dump/restore, smaller fs
Summary: Yes, it is possible

In article <482@cos.COM>, *I* wrote:
> Can I dump [a] file system, make it smaller, and restore my dump onto
> that (smaller) file system?

The answer is: Yes it is possible (at least for BSD 4.2 or later systems).

Cavaets: You have to make sure that is enough space in the new file
system for all of the files in the old file system, PLUS space for the
restoresymtable.

Note: You must do a level 0 dump after restoring the partition.

I think that Guy Harris said it best:

	One problem is that "restore" has a symbol table that it keeps
	around in the file system it's working on; it does this so that
	if you restore a full dump and then an incremental dump, it
	will not only know that some files *changed* or were *added*
	between the full and incremental dumps, it will also know that
	some files were *deleted* between the dumps, and can *remove*
	those files as part of restoring the incremental dump.

	Unfortunately, this symbol table can be very big, which means
	you need enough space on the partition for all the files *and*
	for the symbol table.  (The astute reader will note that this
	can make it impossible to restore a full dump of a partition
	back onto that partition after re-"newfs"ing that partition.)
	Unfortunately, there is no way to say "put that thing somewhere
	else!".

Thanks for answers from:
	David S. Hayes <merlin@hqda-ai.UUCP>
	Kyle Jones <kyle@xanth.cs.odu.edu>
	Guy Harris <guy@sun.com>
	Chris Torek <chris@mimsy.umd.edu>
	James P. Kiely <kiely@lownlab.harvard.edu>
	Dave Marquardt <dave@rosevax.Rosemount.COM>
	Keith DeJager <uunet!rutgers!EDDIE.MIT.EDU!gatech!sunatl!suntri!dj>
	Roger Rose <uunet!EDDIE.MIT.EDU!gatech!stcvax!rlr>

Thanks again for help from the net.
-- 
	--asp (Andrew Partan @ Corporation for Open Systems)
	-- asp@cos.com
	-- {uunet, sundc, decuac, hqda-ai, hadron}!cos!asp