*BSD News Article 63658


Return to BSD News archive

Newsgroups: comp.unix.bsd.freebsd.misc,comp.os.linux.development.system
Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!bunyip.cc.uq.oz.au!munnari.OZ.AU!uunet!in2.uu.net!newsxfer2.itd.umich.edu!newsfeed.internetmci.com!news.mathworks.com!zombie.ncsc.mil!nntp.coast.net!swidir.switch.ch!swsbe6.switch.ch!surfnet.nl!sun4nl!rnzll3!sys3.pe1chl!rob
From: rob@pe1chl.ampr.org (Rob Janssen)
Subject: Re: The better (more suitable)Unix?? FreeBSD or Linux
X-Newsreader: NN version 6.5.0 (NOV)
Reply-To: pe1chl@wab-tis.rabobank.nl
Organization: PE1CHL
Message-ID: <DnoqB4.2sy@pe1chl.ampr.org>
References: <4gejrb$ogj@floyd.sw.oz.au> <4gilab$97u@park.uvsc.edu> <4giqu8$aqk@park.uvsc.edu> <4gira2$a9d@park.uvsc.edu> <hpa.31321eee.I.use.Linux@freya.yggdrasil.com> <4h7t5i$qoh@park.uvsc.edu>
Date: Sun, 3 Mar 1996 09:28:15 GMT
Lines: 37
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:15523 comp.os.linux.development.system:19458

In <4h7t5i$qoh@park.uvsc.edu> Terry Lambert <terry@lambert.org> writes:

>I submit that not losing metadata is a prerequisite to not
>losing data.

>I further submit that files are container objects, and it is
>optional whether or not the file system implements data
>reliability as well (using journalling, logging, transaction
>tracking, or some other as-yet-undiscovered techinque).

>Now I agree that it is *also* optional whether the file system
>guarantees metadata integrity (hence the -async option).

>But I claim that without a guarantee of metadata integrity,
>it's impossible to implement a system that guarantees data
>integrity of data stored in a file system container object
>(file).

I claim that metadata integrity is normally next to useless when there
is no corresponding data integrity.
What use will it ever be to keep your sacred "container object" when
there is just thrash in the container????

Database systems that use their own method for data reliability will
normally not create/remove/extend those files too often, so they don't
benefit from sync metadata either (they just shuffle around data in a
prepared diskfile, for which the access times are the only metadata
items ever updated).  They can just do an fsync whenever it is required.

I still think sync metadata is only a waste in speed that will never
buy you anything in reliability.

Rob
-- 
+------------------------------------+--------------------------------------+
| Rob Janssen         rob@knoware.nl | BBS: +31-302870036 (2300-0730 local) |
| AMPRnet:       rob@pe1chl.ampr.org | AX.25 BBS: PE1CHL@PI8WNO.#UTR.NLD.EU |
+------------------------------------+--------------------------------------+