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

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 4:47 UTC (Mon) by flewellyn (subscriber, #5047)
In reply to: Garrett: ext4, application expectations and power management by neilbrown
Parent article: Garrett: ext4, application expectations and power management

Or, we could use filesystems like, well, filesystems. And if we want databases, we use databases.

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Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 4:58 UTC (Mon) by neilbrown (subscriber, #359) [Link] (5 responses)

What would you suggest is the key difference between the two, which would allow people to decide which to use in a particular situation? In my view they have fairly independent strengths, and if we could unify them that would be useful.

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 9:49 UTC (Mon) by mjthayer (guest, #39183) [Link]

I think that a database lends itself better to indexing than most filesystems, notwithstanding indexing daemons running in the background and holding millions of inotify fds.

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 17:56 UTC (Mon) by flewellyn (subscriber, #5047) [Link] (2 responses)

That's a fair question. I think the main issue is the level of abstraction: databases are more abstract than filesystems, and depend on properly working filesystems for their correct operation. A database is one particular application of data storage, while a filesystem is a general mechanism for data storage.

Garrett: ext4, application expectations and power management

Posted Mar 17, 2009 14:46 UTC (Tue) by Wol (subscriber, #4433) [Link] (1 responses)

Data bases depend on filesystems for their correct operation?

What about native Pick, where the database IS the filesystem?

Or Oracle, where it's configured to use raw partitions for data storage?

Cheers,
Wol

Garrett: ext4, application expectations and power management

Posted Mar 17, 2009 17:58 UTC (Tue) by flewellyn (subscriber, #5047) [Link]

I'd argue that those databases implement their own filesystems.

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 18:44 UTC (Mon) by larryr (guest, #4030) [Link]

Good support for using the filesystem as an efficient mechanism for a persistent hierarchical collection of named values is what I would like. Where the names are the filenames and the values are the file contents. Similar to sysfs. I think a lot of people are using sqlite or dbm files for this because using filesystem operations takes too long.

Larry@Riedel.org

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 14:57 UTC (Mon) by flammon (guest, #807) [Link] (1 responses)

Too bad Hans is in jail because I think that Reiser4 was designed to address the many small files problem with something called block sub-allocation http://en.wikipedia.org/wiki/Block_suballocation. Maybe we can salvage a few ideas from Reiser4.

Garrett: ext4, application expectations and power management

Posted Mar 16, 2009 18:30 UTC (Mon) by job (guest, #670) [Link]

Btrfs has that feature as well, according to documentation.