Martin Matuska <m...@freebsd.org> wrote:
> Tim Cook <tim <at> cook.ms> writes:
>
> > You are not a court of law, and that statement has not been tested. It is
> your opinion and nothing more. I'd appreciate if every time you repeated that
> statement, you'd preface it with "in my opinion" so you don't have people
> running around believing what they're doing is safe. I'd hope they'd be smart
> enough to consult with a lawyer, but it's probably better to just not spread
> unsubstantiated rumor in the first place.
> >
> > --Tim
>
> Hi guys, I am one of the ZFS porting folks at FreeBSD.
>
> You might want to look at this site: http://www.sun.com/lawsuit/zfs/
>
> There are three main threatening Netapp patents mentioned:
> 5,819,292 - "copy on write"
> 7,174,352 - "filesystem snapshot"
> 6,857,001 - "writable snapshots"
>
> You can examine the documents at: http://www.sun.com/lawsuit/zfs/documents.jsp
And people should note that Netapp filed their patents starting from 1993. This
is 5 years after I started to develop WOFS, which is copy on write. This still
is 2 years after a working WOFS implementation has been shown by me at the
Techische Universität Berlin and 2 years after I published my Dimplma thesis
for WOFS.
The most important part of a COW filesystem is to invent a method to reliably
retrieve the most recent super block. The related invention in WOFS is from
1989.
As WOFS was designed for WORM media, all super blocks stay available for ever
and as a result, each "stable sync state" in WOFS could be called a "filesystem
snapshot" that is created without costs. Being able to mount a snapshot
different from the most recent one would no be more than 10 additional lines of
code and is a trivial non-patentable extra effort.
As every "stable sync state" in WOFS is is an "equal snapshot", there is no
special state in the most recent sync state that prevents other sync states
from being written too.
I cannot see any invention from Netapp. They just reimplement prior art.
In any case, this is 20 year old technology. Aren't patents something to
protect new ideas?
Jörg
--
EMail:jo...@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
j...@cs.tu-berlin.de (uni)
joerg.schill...@fokus.fraunhofer.de (work) Blog:
http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/private/ ftp://ftp.berlios.de/pub/schily
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