[FreeVMS] Re: cluster hooks

Subject: [FreeVMS] Re: cluster hooks
From: Bruce Allen (claudevms@home.com)
Date: Thu Nov 15 2001 - 00:43:11 CET

I have the book and I read it almost cover-to-cover.
The SCA is very much like DECnet in structure.

There is lots of MSCP information in the book.
I paid $180.00 for it. I had an out of print bookstore
photocopy it for me. The company has exclusive rights to the book
and they charge whatever they want for it.

Clustering is the key under pinnings for VMS. With version 4 clustering
became the foundation
for VMS. in the earlier versions VMS had a single ACP detached process that
handled I/O.
All processes were forced to context switch to do I/O. Version 4 introduced
clustering, distributed lock management and
the extended QIO (XQP) processor that maps the I/O processing code into all
processes virtual address space. This resulted
in no more context switches to do I/O. The old method of file locking
through FCB bits went away and was replaced by the DLM.
VMS uses the DLM in the XQP to coordinate file locking across the cluster.

I was working on a DLM project a while back where I wanted to build a DLM
that would run in user space instead of Kernel space.
I was hoping to build a DLM that would allow multiple OSes coordinate locks.
Of course they couldn't share file locks only application created locks.

At some point clustering will need to be incorporated and the DLM built on
top of it since we want to do file locking the same way.

This topic is bottomless and is a hugh part of the project.

I also have the McCoy file system book for ODS-2. This book explains the

----- Original Message -----
From: <roart@nvg.ntnu.no>
To: <freevms@ml.free.fr>
Sent: Wednesday, November 14, 2001 7:22 AM
Subject: [FreeVMS] cluster hooks

> Hi
> We might start thinking about clustring; meaning doing some hooks?
> (Like DEC did in the beginning)
> (See figure
> Is the content of following url right?
> http://minnie.tuhs.org/Quasijarus/vaxhw/mscp_clu.html
> Are the MSCP specs available anywhere?
> Has anyone got VAXcluster principles by Roy Davis?
> The price of this book hurts a bit nowadays.
> -Roar Thronæs
> --
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