Article 64058 of comp.os.vms:
Path: jac.zko.dec.com!usenet
From: foley@axel.zko.dec.com (Michael A. Foley)
Newsgroups: comp.os.vms
Subject: Re: Is PCSI robust ?
Date: 29 Jun 1995 20:33:01 GMT
Organization: Integrated Servers Group
Lines: 83
Distribution: world
Message-ID: <3sv2lt$qop@jac.zko.dec.com>
References: <1995Jun21.143922.14851@vms.eurokom.ie> <3scc3n$673@jac.zko.dec.com> <3sebpl$72a@post.gsfc.nasa.gov> <3sf74l$ajr@jac.zko.dec.com> <3sm8d7$6k7@post.gsfc.nasa.gov> <3sn0eo$hp2@jac.zko.dec.com>,<DAtzp1.G6F@boss.cs.ohiou.edu> <3sq6n0$ecr@jac.zko.dec.com> <3srj0r$b40@charon.pjm.com>
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In article <3srj0r$b40@charon.pjm.com>
mixsr@pjm.com (Scott R. Mix) wrote:


> This is interesting ... last year at the Anaheim DECUS, Andy Goldstein said 
> that VMS Engineering uses multiple disks in its definition of SYS$SYSROOT 
> (specifically to allow layered products off the system disk), and if that 
> capability were to cause problems, VMS engineering would grind to a halt.
> 
> -- 
> Scott R. Mix                         "These meanderings reflect the views of

	That method Andy described is called a "Folk" disk. Based on
	the term "Folklore". It's actually a VERY neat way of managing
	a cluster. Basically, you are doing is this:

	Create a disk with the full VMS directory structure. There
	is even a command procedure to help you in the VMS distribution.
	(SYS$SYSTEM:VMS$CREATE_SYSDIRS.COM) This is your "folk"
	disk, the disk that all software will be installed too. It is 
	referred to as CLU$COMMON:

	Then, with some command procedure magic, you redefine
	logical names to include CLU$COMMON at the end of
	the SYS$COMMON logical name. (SYS$SYSROOT is NOT modified.
	It's SYS$COMMON that is. Here is an example of what SYS$SYSROOT
	looks like:

Axel> sho log sys$sysroot
   "SYS$SYSROOT" = "DSA1:[SYS0.]" (LNM$SYSTEM_TABLE)
        = "SYS$COMMON:"
1  "SYS$COMMON" = "DSA1:[SYS0.SYSCOMMON.]" (LNM$SYSTEM_TABLE)
        = "CLU$COMMON:"
2  "CLU$COMMON" = "DSA10:[SYS0.]" (LNM$SYSTEM_TABLE)

	Additional "magic" allows VMSINSTAL.COM to install software to the
	folk disk. (Support is in there, I saw to that :)) Look in VMSINSTAL.COM 
	for VMI$$NO_ROOT.

	What ends up happening is that you can have a system disk with 
	virtually nothing other than VMS and 2 command proceedures on it
	and another disk that has all your software on it. 

	I used to be a ("the" for a while)) system manager in VMS Development, 
	and then worked on bringing clusters to their knee's on the VMS 6.0
	project. (The "Dr. Kevorkian of VMSclusters" :)) I can't take credit for 
	inventing this, but I did make a number of bugfixes and enhancements
	 to the "folk" disk environment to make it more reliable and easier
	to manage.

	I'm hoping that for the next freeware CD to have it all packaged up 
	and some rudimentary documentation written for it. I'll also supply a
	set of procedures that will allow you to build system disks with new 
	versions of VMS. I'm not sure how that will work with PCSI tho. That came
	into vogue after I left VMS. When I was running the VMSINT:: cluster in
	VMS, I could build 3 new system disks at a new baselevel of VMS 6.0
	in about 1 hour and reboot the cluster nodes one at a time to
	the new version. At the time, VMSINT:: was probably the most
	interesting cluster around. Dual FDDI, Dual Ethernet, probably
	close to a terabyte of disk space, 5 VAX6000's, 1 VAX 9000-440 with
	4 vector processors, etc.. You name it, it was on the VMSINT cluster.
	We shook out ALOT of bugs in the I/O subsystem in VMS 6.0 with
	that cluster.

	If you ever get the chance, check out Skip Morris' presentation at
	a DECUS near you on this. Skip is my old roommate and I helped
	him get started with using a "folk" disk.

	FWIW, I use a "folk" disk now on my personal VAX in my office.

	As always, when this is on the freeware CD, it'll be a "use at
	your own risk" affair. I can't provide official support but I'll be glad to
	answer questions here in this newsgroup on it. 

                                                                                         mike
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Michael A. Foley                      
foley@axel.zko.dec.com         AXEL::FOLEY
Integrated Servers Group        W: 603.881.2176
DEC Internal home page:         http://axel.zko.dec.com/~foley/foley.html
|d|i|g|i|t|a|l|                               *Formerly in VMS Development*
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