Re: Read-only ReiserFS support for FreeBSD 5.x

From: Alexander Leidinger <Alexander_at_Leidinger.net>
Date: Wed, 20 Oct 2004 14:43:58 +0200
Zitat von Dan Nelson <dnelson_at_allantgroup.com>:

> Journalled filesystems may guarantee that the filesystem will be
> consistent to a particular point in time, so if your editor updates
> (for example) rc.conf by creating a new copy named rc.conf.new,
> deleting rc.conf, then renaming the copy to rc.conf, you are guaranteed
> that either rc.conf or rc.conf.new will be in the filessytem after a
> crash.  With softupdates, you may lose both files.  I don't know if
> current journalled fses actually journal all writes like this (as
> opposed to just journalling what the OS decides to flush out of its
> cache), but they are much less likely to lose files the way softupdates
> can.

Sorry, this isn't true. Renaming a directory entry is an atomar operation.
Not only "man 2 rename" tells you about it, the softupdates algorithm
guarantees this too. If you move/rename an entry into another directory,
you may have both entries with the same content, but you won't loose both.

Bye,
Alexander.

-- 
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Received on Wed Oct 20 2004 - 10:44:29 UTC

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