  High Availability? Shadowing, Clustering? 
 The Question is:
 
What is VMS Disaster Tolerant Clustering?  Is it part of the base OpenVMS
 operating system or an add-on?  If an add-on, how much does it cost?
 
What is VMS Shadowing?  Once again, part of Open VMS or an add-on?  If an
 add-on, how much?
 
My environment consists of 1 GS140 w/3 processors and 16 gb of memory and 1
 Alpha 8400 with the same configuration.  They are currently clustered locally.
  For DR, I'm thinking about separating them and replicating the GS140 to the
 8400.  I understand tha
t I'll need to purchase a second disk array, but what else?
 
Thanks.
 
Dave Meyer.
 
 The Answer is:
 
  Disaster-tolerant clustering is a Compaq Services offering comprised
  of services and layered software that extend OpenVMS Cluster capabilities
  for use in environments that may encounter catastrophic failures, with
  causes of the failures ranging from fires to earthquakes to criminal
  activities.
 
  http://www.compaq.com/services/available/av_tolerant.html
 
  Packaged and licensed separately.
 
 
  OpenVMS Volume Shadowing provides a single logical volume built from
  multiple physical volumes.  Disks can be local to the same host, or
  can be configured on any host in an OpenVMS Cluster Environment.
  Volume Shadowing can also be refered to as disk mirroring.
 
  The Compaq Volume Shadowing for OpenVMS Software Product Description
  (SPD) is SPD 27.29.xx:
 
    http://www.compaq.com/info/SP2729/SP2729PF.PDF
 
  Volume shadowing is packaged with OpenVMS, with various licenses
  available.
 
 
  Other areas of potential interest include various RAID controllers,
  Data Replication Manager (DRM), VersaStore, and Compaq SANworks
  Virtual Replicator and similar.
 
 
  Also of interest will be a whitepaper on High Availability:
 
  http://www.openvms.compaq.com/openvms/whitepapers/high_avail.doc
 
