From: gjr@zurich.ai.mit.edu (Guillermo J. Rozas)
Newsgroups: comp.sys.hp
Subject: Re: clusters, etc.
Date: 9 Jan 93 08:32:36
Organization: M.I.T. Artificial Intelligence Lab.
Reply-To: gjr@zurich.ai.mit.edu
NNTP-Posting-Host: chamartin.ai.mit.edu
In-reply-to: perry@hpfcmgw.FC.HP.COM's message of Sat, 9 Jan 1993 00:05:46 GMT

In article <17780308@hpfcmgw.FC.HP.COM> perry@hpfcmgw.FC.HP.COM (Perry Scott) writes:

|   From: perry@hpfcmgw.FC.HP.COM (Perry Scott)
|   Date: Sat, 9 Jan 1993 00:05:46 GMT
|   I don't work near the people that are investigating NFS Diskless so I'm
|   not an expert.  The negative feedback I have gotten from customers is:
|
|   1) Not industry standard
|   2) Diskless doesn't work through IP routers
|   3) CDFs are yet another implementation.  It could be done with a
|      dedicated root file system and symlinks/mountpoints.
|
|   There are also some internal disadvantages to HP in supporting diskless
|   in addition to industry standard NFS.

We have a cluster with approximately 30 workstations (300s and 700s).
Before we clusterized our workstations (a few years ago), all
workstations booted locally and used NFS to mount the server's file
systems.

We had all sort of kludges for sharing files and for having some
machines use specific versions, and required great pains and time when
updating the operating system or major software components.

It was an incredible headache!

The cluster software made our lives considerably easier.  I usually
mention it to everyone who asks about HP equipment as one of the
strongest selling points.

What does the cluster software buy us:

- A reliable, consistent, fast network file system.  I've had horrible
problems with NFS on HPs, Suns, and other hardware, and NFS is
considerably slower.

- Easy upgrade and maintenance (changing /etc/netlinkrc, for example)
because there is only one copy of the system (or two for heterogenous
clusters).  Any other software that allows machines to boot over the
network but have local swap disks could probably accomplish this as
well, but the cluster software does this beautifully.

- Easy way to share configuration files and to disambiguate those that
should not be shared by using CDFs.  The MIT AI lab also has a large
Sun setup, and all the /var directories and mesh of symlinks are a
very poor solution compared to CDFs.

- Trivial addition of new machines to our setup.  When we obtain new
machines, it usually takes < 10 minutes to have them working as part
of the cluster with everything set up.  Note that this is the only
thing we use SAM for here, and I wish I did not have to use it for
this either.


I'm not so attached to cluster software that I will be unhappy with
anything else, but I would consider it a large step backwards to have
to put up with:

- an unreliable and slow network file system,

- having to upgrade 30 machines every time there is an operating
system upgrade or configuration change, rather than just one,

- no real way to disambiguate shared files,

- lack of software to conveniently integrate a new machine into our
setup.


In other words, HP, if you do away with cluster software, please make
sure that you don't throw away the features mentioned above.