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From: avg@hq.demos.su (Vadim G. Antonov)
Newsgroups: comp.unix.questions,comp.unix.sysv386
Subject: Re: Reliability of System V 1K file system
Keywords: System V, reliability, file systems
Message-ID: <1990Sep22.160132.24999@hq.demos.su>
Date: 22 Sep 90 16:01:32 GMT
References: <5869@suns302.cel.co.uk> <1990Sep22.041723.1599@pilikia.pegasus.com>
Reply-To: avg@hq.demos.su (Vadim G. Antonov)
Organization: DEMOS, Moscow, USSR
Lines: 24

In article <1990Sep22.041723.1599@pilikia.pegasus.com> art@pilikia.pegasus.com (Art Neilson) writes:
>Every UNIX I have seen behaves in the manner you describe.

	Hmmm... May be your path never crossed some UNIXes?
	For example Unix BSD 4.2 and later has a different file system
	structure which handles power fails more carefully.
	Another example is BSD 2.9 - it has file structure similar
	with v7's (but with 1Kb blocks). The main difference is in
	algorithms: the 2.9's kernel performed critical file system
	operations in the strict order - for exmaple it guarantees
	that if you delete a file inode will be cleared before releasing
	data blocks which in turn will be done before releasing this inode.
	Thus if power would fail during removing a file the worst thing
	which can happen is missed blocks - but generally file structure
	will remain correct. There are some similar tricks in BSD 2.9,
	but I do not want to describe it - get sources and read it
	yourself. Hmmm... +1 to BSD over SysV. (What's a pity there are
	no BSD on 386s!)
					 \ |\/| /
	Vadim Antonov                   -_(____)_-     The actual image
	DEMOS, Moscow, USSR             (        )     of my cat.
	(It is NOT a joke!)          -------||-------
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