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Date:      Tue, 5 May 1998 08:16:48 +0000 (GMT)
From:      Terry Lambert <tlambert@primenet.com>
To:        tom@sdf.com (Tom)
Cc:        beng@lcs.mit.edu, freebsd-hackers@FreeBSD.ORG
Subject:   Re: Network problem with 2.2.6-STABLE
Message-ID:  <199805050816.BAA19281@usr02.primenet.com>
In-Reply-To: <Pine.BSF.3.95q.980504210155.20203C-100000@misery.sdf.com> from "Tom" at May 4, 98 09:09:15 pm

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>   Perhaps, but dump/restore is broken for large filesystems.  Perhaps one
> of the dump/restore advocates should fix it before a new user is swayed by
> the rhetoric into using dump/restore, only to watch restore core dump on
> large dumps.

Be happy to.  Where is you real bug report that details the problem,
instead of just stating that there is one?  So far, all I have seen
is a bit of FUD with no real basis below 1TB -- far out of the range
claimed for the problem (4GB, which doesn't make sense anyway, since
indirect blocks are negated, so at best you could claim 2GB because
of the sign, IFF dump operated on byte offsets instead of block
offsets, which it doesn't).

>   Other problems with dump/restore:
> 
> - Tape format is specific to dump, and can't be read anywhere else.  The
> current large filesystem bug could be a data structure problem, which in
> order to fix will break compatibility with old tapes!

No.  You write a different header that indicates that you are going
to be using 63 instead of 31 bit offsets.  The different header is
only written in the case that the FS is large enough to trigger the
alleged problem.


> - You need to be read permissions to the raw filesystem to run dump.

This is not a bug, it is a feature.

If I can dump an FS without read permiision, I can take the tape to my
own box and violate system security by reading the tape in there, where
I have root privs.

PS: how did you get write access to one raw device (the tape drive)
an find yourself unable to get read access to a different raw device?

PPS: sudo.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.

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