Re: what is our answer to ZFS?

From: Jörn Engel
Date: Mon Nov 21 2005 - 05:19:45 EST

On Mon, 21 November 2005 01:59:15 -0800, Alfred Brons wrote:
> I wasn't aware of this thread.
> But my question was: do we have similar functionality
> in Linux kernel?

If you have a simple, technical list of the functionality, your
question will be easily answered. I still haven't found the time to
dig for all the information underneith the marketing blur.

o Checksums for data blocks
Done by jffs2, not done my any hard disk filesystems I'm aware of.

o Snapshots
Use device mapper.
Some log structured filesystems are also under development. For
them, snapshots will be trivial to add. But they don't really exist
yet. (I barely consider reiser4 to exist. Any filesystem that is
not considered good enough for kernel inclusion is effectively still
in development phase.)

o Merge of LVM and filesystem layer
Not done. This has some advantages, but also more complexity than
seperate LVM and filesystem layers. Might be considers "not worth
it" for some years.

o 128 bit
On 32bit machines, you can't even fully utilize a 64bit filesystem
without VFS changes. Have you ever noticed? Thought so.

o other
Dunno, what else they do. There's the official marketing feature
lists, but that's rather useless for comparisons.


Measure. Don't tune for speed until you've measured, and even then
don't unless one part of the code overwhelms the rest.
-- Rob Pike
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