*BSD News Article 61874


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From: mbeattie@sable.ox.ac.uk (Malcolm Beattie)
Newsgroups: comp.unix.bsd.freebsd.misc,comp.os.linux.development.system
Subject: Re: The better (more suitable)Unix?? FreeBSD or Linux
Date: 12 Feb 1996 12:51:44 GMT
Organization: Oxford University, England
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Message-ID: <4fnd50$h1f@news.ox.ac.uk>
References: <4er9hp$5ng@orb.direct.ca> <hpa.31167ef4.I.use.Linux@freya.yggdrasil.com> <4fdupc$e36@news1.wing.net> <JRICHARD.96Feb9101113@paradise.zko.dec.com>
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:14134 comp.os.linux.development.system:17757

In article <JRICHARD.96Feb9101113@paradise.zko.dec.com>,
John Richardson <jrichard@paradise.zko.dec.com> wrote:
>
>
>> 
>> : mostly because it really turns out that BSD-style synchronous metadata
>> : updates are slow and buy you very little in terms of data safety, and
>> : can, in fact, be a security hole.
>> 
>> whoa -- that's a big accusation for a filesystem that's been relied
>> on and worked on by a lot of people for a lot of time.  what exactly
>> are you referring to?  color me skeptical.  (but willing to learn.)
>
>
>Since the metadata is written out before the actual data, if the
>machine crashes before data is written, the metadata may point to
>bogus data.  This means you may have access to data that someone else
>thought was deleted.
>
>
>-- 
>John Richardson                jrichard@zko.dec.com
>Digital Equipment Corporation  (603) 881-0168
>Nashua, NH

As a humorous but genuine example of that, I include a user's message
(suitably anonymised) that we received after our 2100 (running Digital
UNIX with the BSD FFS) crashed in December.

> Date: Fri, 1 Dec 1995 15:20:20 GMT
> From: J Random User <jruser>
> Apparently-To: root
>
> I know funny things happen after crashes, but this is a new one on me.
> My .pinerc file now contains lots of ascii pictures of cows.
> Please can I have the old one back?
> I haven't had time to look at many of the other files - do you think I should?
> Thanks
>
> Random User

We restored the user's real .pinerc from backup but another of our users
must still be missing those cows.

--Malcolm

-- 
Malcolm Beattie <mbeattie@sable.ox.ac.uk>
Oxford University Computing Services
"Widget. It's got a widget. A lovely widget. A widget it has got." --Jack Dee