Maybe not [LWN.net]

Maybe not

Posted Mar 17, 2009 21:40 UTC (Tue) by man_ls (subscriber, #15091)
In reply to: Better than POSIX? by xav
Parent article: Better than POSIX?

Maybe the answer is a new set of guarantees for Linux's POSIX API, e.g. an overwriting rename() will either leave the old or new version to disk, atomically.

Why? As has been pointed out, ext2 is perfectly fine for many applications, and it would never be Linux-POSIX-compliant this way. For example in data centers with 3-way redundant power supplies and redundant storage, or temporary filesystems.

Do you really think it is better to force everyone to comply with a new standard than trying to convince ext4 developers to do the (obvious) right thing?

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ext2, Bruté?

Posted Mar 18, 2009 22:57 UTC (Wed) by xoddam (subscriber, #2322) [Link]

I can think of no reason at all why a guarantee of this sort should not be considered desirable for any filesystems that try to ease crash recovery. It may be out of ext2's reach (because its code does not impose a strict partial ordering on disk writes), but it should be achievable as an enhancement to any journaling, log-structured or soft-update filesystem.

ext2, Bruté?

Posted Mar 18, 2009 23:25 UTC (Wed) by man_ls (subscriber, #15091) [Link]

It is by all means desirable. The proper place for such a standard might be debated though. I have always understood that POSIX is a standard for compatibility, e.g. Wikipedia says:

POSIX or "Portable Operating System Interface for Unix"[1] is the collective name of a family of related standards specified by the IEEE to define the application programming interface (API), along with shell and utilities interfaces for software compatible with variants of the Unix operating system, although the standard can apply to any operating system.

So I don't know if a standard for reliable file systems would fit in.