[OpenAFS] AFS vs DAV

[Rodney M Dyer]

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
Phone (704)687-3518
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