Linux for 'cloud computing': Request for Input

[Ken D'Ambrosio]

On Fri, March 5, 2010 3:12 pm, Jon 'maddog' Hall wrote:

> It has been some time since I have looked at file systems, and
> particularly COW file systems, so pardon me if these questions are
> "naive".
>
> Any traction to ext3cow or using the COW layering capability of the UDB
> block driver? Or LVM "snapshots"?

I'd say non-btrfs COW solutions are being back-burnered.  When Ted T'so
(for example), primary guy behind ext-4, says it's a stopgap until btrfs,
you get the idea that folks are hot for it.  And with people like Valerie
Aurora (a former ZFS developer) watching closely and offering advice, you
hope that they get things right.

> And I can not remember if GFS (Global File System, or even the Google
> File System) was COW.

Dunno.

> Finally, what about the up and coming Btrfs?

See above.  It's coming.  I'd say that, by fall, you could start using it
as your primary, non-server filesystem.  Since folks are (understandably)
very conservative about filesystems, it'll probably be another two years
before it's a primary install option, but it's coming.  It's got some
truly neat features:
- COW
- Explicit/online defragmentation (volume or file)
- Filesystem-aware RAID (you can even alter RAID on a per-file basis)
- VERY flexible, filesystem-aware snapshotting
- Online fsck
- Checksums (yay!)
- (File-level) de-duplication; block-level is being discussed, but
apparently would require an on-disk format change, so that's probably a
major rev away.  (Ken's guess.)
- Etc.  See the Wikipedia page or the btrfs Wiki for more info.
(http://en.wikipedia.org/wiki/Btrfs and http://btrfs.wiki.kernel.org ,
respectively.)

-Ken


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