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From: Terry Lambert <terry@lambert.org>
Newsgroups: comp.unix.bsd.freebsd.misc,comp.os.linux.development.system
Subject: Re: The better (more suitable)Unix?? FreeBSD or Linux
Date: 14 Feb 1996 21:23:53 GMT
Organization: Utah Valley State College, Orem, Utah
Lines: 57
Message-ID: <4ftjt9$fjs@park.uvsc.edu>
References: <4er9hp$5ng@orb.direct.ca> <4fg8fe$j9i@pell.pell.chi.il.us> <311C5EB4.2F1CF0FB@freebsd.org> <4fjodg$o8k@venger.snds.com> <4fo1tu$n31@news.jf.intel.com> <DMrCE4.3HF@pe1chl.ampr.org>
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:14254 comp.os.linux.development.system:17869
rob@pe1chl.ampr.org (Rob Janssen) wrote:
] The claim is that the synchronous metadata updates are undesirable,
] because they slow down the system, and whatever consistency advantages
] they are said to have only make it more likely that fsck will report no
] errors, and don't improve the situation w.r.t. bogus data.
Let us agree that synchronus updates are undesirable.
Let us also agree that the UFS use of synchronus updates is as
a simple method of ensuring write ordering without violating
patents or rewriting a lot of code.
Let us discuss the desirability of order metadata writes.
Posit: ordered metadata writes insure the determisitic
recoverability of changes to file system structure,
Conclusion: ordered metadata writea are desirable.
Posit: fsck is a utility to ensure file system structure
integrity.
Posit': fsck has nothing to do with integrity of files as
container objects.
Conclusion: fsck does not improve the situation w.r.t.
bogus data.
Conclusion': the discussion of the situation w.r.t. bogus
data has no bearing whatsoever on the
desirability or undesirability of ordered
metadata writes.
] The claim (usually) isn't that async metadata is better in
] this respect, but it is not worse and it is faster. Hence
] i
Since the recoverability of file system structure is unrelated
to the recovery of data within files as container objects, your
claim about "not worse" applies only to files as container
objects, and is not applicable to the discussion of write
ordering or the use of syncronous I/O as a mechanism used in
the implementation of write ordering.
Your conclusion "Hence it is superior" is thus provably false;
the claims you make and the supporting evidence you use to make
them are orthogonal.
Regards,
Terry Lambert
terry@cs.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.