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DSSI and SCSI are simply connections paths used by the VMScluster
software -- like memory channel, Ethernet, FDDI, CI, etc. DSSI
is a "full" interconnect, as it can be used to communicate with
storage devices, and with other VMScluster nodes. SCSI is a
"storage" interconnect, meaning it can be used to communicate with
storage devices only, and a second interconnect, such as FDDI or
NI, is required.
I strongly recommend reading the hardcopy documentation provided
with the OpenVMS release, particularly with the V7.1 documentation.
There are two VMScluster manuals -- the `Guidelines' manual is the
first one you will want to read for this configuration. It will
go into the correct setting of VOTES and EXPECTED_VOTES, as well
as other necessary configuration steps...
For SCSI VMScluster configurations, you will need OpenVMS Alpha
V6.2-1H3, or V7.1 or later, and SCSI controllers from a specified
set of supported SCSI controllers. (Not all SCSI controllers are
supported.)
When configuring SCSI or DSSI connections in a VMScluster, each
controller and each storage device on the SCSI or DSSI must have
a unique SCSI or DSSI address. How one configures this is host
and controller (and storage device) specific.
With configurations with multiple SCSI controllers present in a
host, each must have the same controller letter in the device name.
(This means some creative configurations, or the same storage
configuration in all nodes connected via SCSI.) The concept of
port-level allocation classes was added in V7.1, and simplifies
this configuration.
Assuming supported controllers and once the addresses are unique,
then all one does is cable the busses together. (Normally, one
disconnects the bus only when it is inactive -- this means that
all systems on the shared bus are shut down, or the bus has been
"quiesced" via an existing SCSI-repeater...)
For suggested and supported approaches on how to back up an Oracle
database, you'll want to contact Oracle.
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