OpenVMS Cluster Systems - OpenVMS Systems - HP

Cluster Storage Devices
6.2 Naming OpenVMS Cluster Storage Devices
to include additional devices types: floppy disks, PCI RAID controller disks, and
IDE disks.
The use of port allocation classes is optional. They are designed to solve the
device-naming and configuration conflicts that can occur in certain configurations,
as described in Section 6.2.3.
To differentiate between the earlier node-based allocation class and the newer
port allocation class, the term node allocation class was assigned to the earlier
type.
Prior to OpenVMS Version 7.2, all nodes with direct access to the same
multipathed device were required to use the same nonzero value for the node
allocation class. OpenVMS Version 7.2 introduced the MSCP_SERVE_ALL
system parameter, which can be set to serve all disks or to exclude those whose
node allocation class differs.
Note
If SCSI devices are connected to multiple hosts and if port allocation
classes are not used, then all nodes with direct access to the same
multipathed devices must use the same nonzero node allocation class.
Multipathed MSCP controllers also have an allocation class parameter, which is
set to match that of the connected nodes. (If the allocation class does not match,
the devices attached to the nodes cannot be served.)
6.2.2 Specifying Node Allocation Classes
A node allocation class can be assigned to computers, HSC or HSJ controllers,
and DSSI ISEs. The node allocation class is a numeric value from 1 to 255 that
is assigned by the system manager.
The default node allocation class value is 0. A node allocation class value of 0
is appropriate only when serving a local, single-pathed disk. If a node allocation
class of 0 is assigned, served devices are named using the node-name$device-name
syntax, that is, the device name prefix reverts to the node name.
The following rules apply to specifying node allocation class values:
1. When serving satellites, the same nonzero node allocation class value must be
assigned to the serving computers and controllers.
2. All cluster-accessible devices on computers with a nonzero node allocation
class value must have unique names throughout the cluster. For example, if
two computers have the same node allocation class value, it is invalid for both
computers to have a local disk named DJA0 or a tape named MUA0. This
also applies to HSC and HSJ subsystems.
System managers provide node allocation classes separately for disks and tapes.
The node allocation class for disks and the node allocation class for tapes can be
different.
The node allocation class names are constructed as follows:
$disk-allocation-class$device-name
$tape-allocation-class$device-name
Cluster Storage Devices 6–7