[Info-vax] Shadow System Disk between two Hosts

[Paul Sture]

On Tue, 15 May 2012 11:45:26 -0600, Keith Parris wrote:

> We have customers with two-site disaster-tolerant OpenVMS clusters where
> the SAN is extended between sites, and some of them choose to boot from
> a common system disk shadowset shadowed across sites. The only caveat I
> have is that with a single system disk for the cluster, it can represent
> a single point of failure for the entire cluster in the event that
> someone accidentally deleted a crucial file or something. So we
> recommend that if you have only a single system disk in the cluster that
> you keep a current backup copy online and accessible that you could
> quickly reboot from if the regular single system disk shadowset were
> damaged.

15 years ago I worked at a place with 2 data centres a mile apart, using 
FDDI for shadowing between the 2 sites.  They had to have separate system 
disks because FDDI didn't work until VMS was up.  I don't remember all 
the gory details, but we did have to suffer full shadow copies (mini-
merge etc weren't around in those days) if either system was rebooted.



-- 
Paul Sture