Messages in this thread |  | | | From | Mirian Crzig Lennox <> | | Subject | scary ext2 filesystem question | | Date | 25 Dec 1998 11:42:57 -0500 |
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I was reading a book on filesystem design, and came across the following scary quote:
"The main difference between ext2 and FFS is that ext2 makes no guarantee about consistency of the file system or whether an operation is permanently on the disk when the file system call completes. [...] This consistency model is not without drawbacks and may not be appropriate at all for some applications. Because ext2 makes no guarantee about the order of operations and when they are flushed to disk, it is conceivable (although unlikely) that later modifications to the file system would be recorded on disk but earlier operations would not be. Although the file system consistency check would ensure that the file system is consistent, the lack of ordering on operations can lead to confused applications or, even worse, crashing applications because of the inconsistencies in the order of modifications to the file system." _Practical File System Design_, Dominic Giampaolo, p. 36
Unfortunately, the author goes into no deeper detail about the danger, and so the above text remains just vague enough to give me a gnawing case of FUD. Would some knowledgeable person on this list care to enlighten me? I'm particularly concerned about how an application could potentially become confused and/or crash because of this.
Even if the danger has only one chance in a thousand million of occurring, I'd still like to understand why the probability is that small, and why it is nonzero, and what, if anything, an application programmer seeking robustness could do to work around it.
-- Mirian Crzig Lennox Systems Anarchist "There's a New World Order coming every minute. Make mine extra cheese."
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