Re: VMS analogue of FBSD and linux hier(7) man pages

Ken Fairfield wrote:
Richard B. Gilbert wrote:
[...]

I would answer by saying that the structure of the system disk is common to all VMS Systems. It has been this way since at least VMV V3.6 (ca. 1984). There are "system roots": SYS0 by default for a standalone system. SYSE is conventionally standalone backup. SYSF is used for installations and upgrades. SYS1-SYSC are optional on a VMS Cluster system disk; one root for each system in the cluster. The "system root" directories hold files specific to a particular cluster member. All the standard system directories are twinned in SYS$SPECIFIC and SYS$COMMON trees. the SYS$SPECIFIC tree has files that are specific to a particular system while the SYS$COMMON tree has files common to all. I don't believe I've ever seen more than three systems booting from the same system disk although, in principle, you could have as many as thirteen.


Haven't been around much, eh? :-) :-)

> A cluster could have one system disk for each node in the

cluster or small cluster could share a common system disk (disk loading would make this impractical in a large cluster) imagine fourteen nodes beating up the same system disk, it would run like a dog!


At my previous, previous employment, we had 2 Alpha 4100's on one
system disk, and 3 VAX 6000-class machines on another (of course)
system disk, all on the CI. But we also had 30 VAXstations (3100's
and 4000 VLC's) _also_ booting from the VAX system disk. In other
words, there were 33 or so system roots on the VAX system disk.

How did it perform? How long did it take to boot?

Few of my previous employers could afford that much hardware or that many software licenses! My largest employer was the F.W. Dodge division of McGraw-Hill in Hightstown, NJ. We had twenty-five systems in the data center and approximately 100 field offices, each with its own VAX Cluster. The field offices all had a MicroVAX 3100 and one or more VAXstation 3100s. No cluster in the data center had more than three nodes or two system disks. They were the exception. My last employer had seven Alphas: 2 ES40s (clustered) 3 4100s (2 clustered), an Alphaserver 2100 and an Alphaserver 2000.

So the largest cluster I've "seen" had ten or so nodes and would have been one of the larger McGraw-Hill/F.W. Dodge field offices. I never laid eyes on it; we managed these clusters remotely using a long forgotten product called RSM (Remote System Manager).

While, in principle, it may be possible to run several dozen machines off the same system disk, it does not seem very practical.

.

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