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From: shannon@sun.uucp (Bill Shannon)
Newsgroups: comp.unix.wizards
Subject: Re: Backups on Live Systems
Message-ID: <20070@sun.uucp>
Date: Sun, 31-May-87 02:35:42 EDT
Article-I.D.: sun.20070
Posted: Sun May 31 02:35:42 1987
Date-Received: Tue, 2-Jun-87 01:23:24 EDT
References: <132@dvm.UUCP> <725@aramis.rutgers.edu>
Organization: Sun Microsystems, Inc. - Mtn View, CA
Lines: 17
Keywords: backup, dump, filesystem
Summary: how would you do it and what would you expect?

I'm curious, does anyone have any really good ideas about how to
do reliable backups on active filesystems?  Would such backups,
by necessity, have to be done through the filesystem, rather than
through the raw device as dump does?

Also, what would you *expect* from a full dump taken on an active
filesystem?  If you had to restore that dump, what state of the
filesystem would you expect to restore?  What sort of guarantees
of consistency would you want from such a dump scheme?  When the
filesystem is inactive, it's easy to guarantee a certain consistency,
but when it's (potentially very) active, what can you guarantee?

Does anyone know how other systems handle this problem?  What does
VMS do?  TOPS-20?  Multics?  others?

					Bill Shannon
					Sun Microsystems, Inc.