Ho ho!  As much as I like Becker and the boys at CESDIS (Beowulf), now
Scyld, this is pretty interesting.  I don't know if Linux *can* be as
reliable as VMS (whole 'nother can of worms), but the scalability stuff
sure is nifty.

-- 
"To misattribute a quote is unforgivable." --Anonymous

---------- Forwarded message ----------
Date: Fri, 06 Jul 2001 01:46:36 GMT
From: Scott Vieth <svieth at wi.rr.com>
Newsgroups: comp.os.vms
Subject: VMS-style clustering comes to Linux?!?!

This little goodie showed-up in my inbox today:
======================================
In this issue:

* VAX clustering makes a comeback
* Links related to Linux
* Featured reader resource

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Today's focus: A blast from the past

By Phil Hochmuth

Devotees of Digital Equipment were probably saddened when
Compaq announced last week that it would phase out its 64-bit
Alpha chip by 2004. So goes another old DEC technology into the
history books.

However, one group of programmers is bringing another old DEC
technology - namely, VAX clustering - back into use, this
time with Linux.

Under a project called Distributed Lock Manager (DLM), the
creators tout the software as "an implementation of the
classic VAX cluster locking semantics for a Linux cluster."

VAX is DEC's old mini-computer which housed the VMS operating
system and for years was the standard in high-availability
computing in large enterprises, rivaled only by IBM's
mainframe.

The machine was known for its superb clustering capabilities,
which allowed between a dozen and several hundred machines to
be grouped together to act as one large system. Nodes in the
cluster could be brought up and down without notice from end
users, making the cluster very reliable and scalable. While
clustering technology exists today for Unix, Windows and Linux
platforms, many long-time technology observers and users say
that only the VAX ever got it right.

Users with knowledge of VAX cluster administration should find
DLM software familiar. DLM consists of software, a kernel
module and daemon, plus shared API. The shared API runs on each
client that controls the locking and unlocking of resources
hosted by the cluster, such as applications and files. The DLM
software also manages recovery of failed nodes, and the
addition of new nodes to the cluster.

The DLM code was previously used to support IBM's AIX-based
high-availability system. However, with support for eight
nodes, DLM does not match the clustering scale of the VAX, or
even the commercial clustering systems available today.
However, for users looking to put together a smallish, highly-
available Linux cluster with Linux, DLM might be worth checking
out.

While documentation for the software is thin, DLM creators say
some documentation from IBM on its high-availability clustering
is complimentary to the DLM software, and is available at:
http://www.rs6000.ibm.com/software/downloads/ha44lock.pdf

_______________________________________________________________
To contact Phil Hochmuth:

Phil Hochmuth is a staff writer for Network World, and
a former systems integrator. You can reach him at
mailto:phochmut at nww.com.
_______________________________________________________________
RELATED EDITORIAL LINKS

Check out the DLM web page
http://oss.software.ibm.com/developerworks/projects/dlm/

Download the software
http://oss.software.ibm.com/developerworks/project/showfiles.php?group_id=27

&release_id=65