From: tcooper@bnr.ca (Terry Cooper)
Subject: Re: clusters, etc.
Organization: Northern Telecom, Ltd.
Date: Mon, 11 Jan 93 01:23:10 GMT

In article <GJR.93Jan9083236@chamarti.ai.mit.edu> gjr@zurich.ai.mit.edu writes:
>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.

I am responsible for a small group of HP workstations, about 150 organised
into 8 clusters.  Most of these stations are 300/400s but we do have about
20 700s (cnodes 705/710/720, servers 730/750).  This is a small sub-set of
the corp installation of HP stations which number in the thousands.  Without
the cluster protocol, management of this number of workstations would be
next to impossible. I know I've tried using NFS, it doesn't work for even
a few (<50) workstations.

On the point of cluster size, we have a mixed cluster of about 25 workstations
(15 700s and 10 300/400s) with a 730 server.  All workstations have internal
disks for local swap, someting I highly recommend.  The server doesn't work up
a sweat but ethernet is proving to be too slow to handle the 700s (we are doing
a lot of 'C' compiles, ie: heavy disk load).  We will be spliting this
workgroup into two in the next couple of weeks with the addition another server
to reduce the load on the LAN (we are using a multiport bridge to split LAN
traffic).
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