Andrew File System (Summ

[nagler at olsen.uu.ch]

The best way to evaluate AFS is to get a trial copy (deferred payment,
actually).  No one was able to tell me if AFS was an improvement over NFS
(except in subjective terms).  File service requirements vary widely from
system to system.

Here's the summary.  If you want the original answers, just send me mail.
They were too long to include here.

Thanks to:
    ittai at shemesh.gba.nyu.edu (Ittai Hershman)
    paw at eleazar.dartmouth.edu (Pat Wilson)
    Kris Olander <kriso at northstar.dartmouth.edu>
    nowicki at Legato.COM (Bill Nowicki)

>1) Can AFS completely replace NFS including booting?...

Yes, but not for diskless clients.  For this, you need NFS/AFS translator
which runs on the server.  Caches don't need to be large unless you deal
regularly with large files (which we do).  

>2) Is it possible to use the one disk as a cache while using the
>   server software on another?...

The client/server software operate independently.  The servers might be
too loaded for interactive use, but this is configuration dependent.

>3) Can you cross-mount and what happens when a "server" goes down?...

When a server goes down, the client times out and looks for "clone"
volumes on the network.  If there are no clones, the user program sees the
error (e.g. like a soft mount).  It isn't clear (to me) if you can
imitate a hard mount.

>4) Do you notice a reduced network load when using AFS in comparison
>   to NFS?...

The subjective answer is yes.

>5) What are the administration headaches?

AFS is not a Unix file system so you can use system utilities like "dump".
Transarc supplies its own dump utilities.  ("tar" works but is too slow
for dumps.) Permissions are on a directory (as opposed to file) basis.
Root is not recognized as a special account by an AFS server.

>6) What's your configuration (briefly)?...

[paw] We run AFS 3.0 (soon to be 3.1) on a network of heterogenous
workstations, which include Suns (3s, 4s, and SPARCs).  We don't NFS mount
_anything_ anymore...

[kriso] IBM (RTs, 6152s, RS/6000), HP9000 (340), Sun (3/280, 3/60, 4/110,
Sparcstations 1), DEC (3100).  I think our best configurations are our
Sparcstations with (2) 107meg disks.  We do have some HP systems running
HP's CNODE diskless environment with AFS mounted via and AFS/NFS
translator which runs on some other diskFULL AFS client.  

>7) Do you recommend purchasing AFS as a part of the OSF/DCE or directly
>   from Transarc?...

Transarc's support is good.  kriso didn't recommend OSF/DCE, because it is
a new.  However, ittai at shemesh.gba.nyu.edu (Ittai Hershman) said, "Like
me, you probably want the AFS in OSF DCE which is NOT the same as the AFS
Transarc is shipping now.  The first release of DCE should be out in the
Summer of 1991."

Finally, nowicki at legato.com recommended I get a Legato PrestoServe board
to improve NFS performance.  It's a VME board and we only have S-Bus,
unfortunately.