[OpenAFS] AFS vs DAV
Rodney M Dyer
rmdyer@uncc.edu
Fri, 16 Jan 2004 17:03:21 -0500
At 11:07 AM 1/16/2004, you wrote:
>I hear that several universities are beginning to use a DAV-based
>institutional file system. The name Xythos has been mentioned.
>
>I am wondering if anyone has done a comparison of features, performance,
>security, and scalability between AFS and DAV. In particular, do the big
>AFS shops of the past still believe that AFS is The Way?
I suppose that depends. It depends on whether you are going to do things
the right way (smart), or do things the wrong way (dumb). Using DAV is
dumb. Using AFS is smart. Yes, I'm showing my butt here. Why?
Let's look at it this way... DAV protocol is an attempt to allow file
sharing over HTTP. However you look at it, you are using a web browser
technology to do your file sharing. I now ask you, how many of you are
running your applications off the web? Word processors? Mathematics and
scientific applications? Graphics and multimedia? No? Then why in the
world would you even attempt to build a file system architecture (which by
many accounts needs to be the most reliable of all your networking
services) over a protocol that was originally only invented to be a
hypertext page display technology? There are so many reasons not to do
this I can't even think straight. This is a perfect example of "just
because you can do something, doesn't mean you should".
AFS was built from scratch as a true enterprise wide network file
system. AFS is designed to be Internet capable. AFS already has SSO,
strong encryption, global namespace, volume replication and location
services, fault tolerance, ACL security, user ACL groups, local caching,
etc. AFS allows your client to be automatically directed to the proper
file server for your volumes so you don't need to go through a silly
gateway server like DAV. DAV is just a poor man's way to grab and drop
files onto a remote file server. DAV was never never intended to be a real
file system in any sense of the word. As someone has already stated in
this thread, DAV is just a copy/lock/sync technology.
Since the web browser was invented many people have been pushing to make
just about everything but the kitchen sink work over that stupid
protocol. From portals to ASP applications, and now file sharing. It just
doesn't make sense to try and rewrite everything to work over port
80. That stupid port is now being layered to death. And, because of this
layering, everything that works over it is s.l.o.w.
I suppose I'm being rash here using words like stupid and dumb, but anybody
who's going to build an enterprise solution for network file sharing should
really think deeply about what technology is best for the job. Don't let
higher management get caught up on buzz word marketed technologies.
DAV is not the solution you are looking for. Almost anything is better
than DAV. Don't do it.
This rant is entirely my own opinion based on years in the trenches as a
systems programmer. Your mileage may vary.
Rodney
Rodney M. Dyer
Windows Systems Programmer
Mosaic Computing Group
William States Lee College of Engineering
University of North Carolina at Charlotte
Email: rmdyer@uncc.edu
Web: http://www.coe.uncc.edu/~rmdyer
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