Re: Transparent compression in the FS

[Larry McVoy]

On Wed, Oct 15, 2003 at 11:13:27AM -0400, Jeff Garzik wrote:
> Josh and others should take a look at Plan9's venti file storage method 
> -- archival storage is a series of unordered blocks, all of which are 
> indexed by the sha1 hash of their contents.  This magically coalesces 
> all duplicate blocks by its very nature, including the loooooong runs of 
> zeroes that you'll find in many filesystems.  I bet savings on "all 
> bytes in this block are zero" are worth a bunch right there.

The only problem with this is that you can get false positives.  Val Hensen
recently wrote a paper about this.  It's really unlikely that you get false
positives but it can happen and it has happened in the field.  
-- 
---
Larry McVoy              lm at bitmover.com          http://www.bitmover.com/lm
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/