Garrett: ext4, application expectations and power management [LWN.net]

Garrett: ext4, application expectations and power management

Posted Mar 15, 2009 20:32 UTC (Sun) by smoogen (subscriber, #97)
In reply to: Garrett: ext4, application expectations and power management by drag
Parent article: Garrett: ext4, application expectations and power management

Of the file systems is EXT3 the only one that does give that promise (and only by accident as it was an unintended consequence)?

xfs would seem not to and btrfs not to (going from the original blog post. I don't know about all types of reiserfs or jfs.

I am not saying the 'promise' is not important.. but it might be one that file-system developers should be aware that people want versus what they think people should expect :)

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Garrett: ext4, application expectations and power management

Posted Mar 15, 2009 23:41 UTC (Sun) by drag (guest, #31333) [Link] (2 responses)

Ya. It seems to me that Ext3 only works that way by accident.

But it seems that for consumer devices this sort of behavior could actually be a fundamental design improvement over the way file systems have traditionally worked and could be advertised as a actual selling point (that is being able to do promise # 2. reliably.)

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 16:12 UTC (Mon) by jspaleta (subscriber, #50639) [Link]

I've always wondered.. how many of the more important or more impactful improvements in technology in the long view of history were simply uncharacteristically happy accidents versus premeditated "design" decisions.

-jef

Garrett: ext4, application expectations and power management

Posted Mar 19, 2009 23:28 UTC (Thu) by jzbiciak (guest, #5246) [Link]

Not really by accident. I believe the necessary dependence is established by the "data=ordered" mount option. That's pretty much what we need to fix this issue: Make sure that the data is on the disk before you write the updated metadata.

That doesn't mean you need to flush things to the disk early. It just means that things have to happen in a particular order.