Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!nrl-cmf!cmcl2!phri!roy
From: roy@phri.UUCP (Roy Smith)
Newsgroups: comp.unix.wizards
Subject: Re: another question about dump & restore
Keywords: dump restore file system
Message-ID: <3339@phri.UUCP>
Date: 8 Jun 88 12:33:18 GMT
References: <5757@umn-cs.cs.umn.edu>
Reply-To: roy@phri.UUCP (Roy Smith)
Organization: Public Health Research Inst. (NY, NY)
Lines: 25

indermau@dg.cs.umn.edu.UUCP (Kurt Indermaur) writes:
> What is an "active file system"?  Nobody logged in? Single user mode?  

	For all intents and purposes, an active file system is one mounted
with write permission.  I believe there have been some mods to the 4.2BSD
dump posted (probably by Don Speck, and probably included in the 4.3
version of dump) which help make dump more immune to file system activity.
Note that this doesn't mean that dump is guaranteed to work properly on an
active file system, just that it is less likely to mess up.

	These changes were a grudging concession to the fact that most
people just can't afford to dismount their user's files every day to do
incrmentals.  For example, we do daily and weekly dumps while the system is
running full-tilt.  Monthlys and quarterlies (the latter being archival
level-0's) are done with the system single-user.

	Also along this line, note that in SunOS-4.0, the system comes up
with root mounted read-only so fsck can work more reliably and is later
changed to r/w for normal use.  Presumably you can do level-0 root dumps
with the root in this read-only state.
-- 
Roy Smith, System Administrator
Public Health Research Institute
455 First Avenue, New York, NY 10016
{allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net