Booting Satellite Nodes from an MSCP Served
System Disk Shadow Set
The OpenVMS
operating system uses the Maintenance Operations Procedure (MOP)
protocol to boot satellite nodes. MOP protocol support is provided
by either the LANACP process controlled by the LANCP utility or
by DECnet software controlled by the NCP or NCL utilities. You must
specify the name of the satellite's system disk using LANCP, NCP,
or NCL commands (depending on which you are using to boot satellites).
If the system disk is shadowed, the commands should specify the
virtual unit or the virtual unit logical name rather than any physical
unit.
The MOP server accesses the system disk shadow set (using
the virtual unit defined) to perform downline load operations to
the satellite. These operations include downline loading the physical
boot device name to the satellite. When downline loading is complete,
the satellite is able to connect to an MSCP server and access the
physical boot device directly. The satellite's shadowing parameters
are then used in the same way as a nonsatellite node.
You
can use the SYS$MANAGER:CLUSTER_CONFIG_LAN.COM procedure or the SYS$MANAGER:CLUSTER_CONFIG.COM
procedure to set MOP server, MSCP server, and satellite parameters
automatically. When configuring satellite nodes with the cluster
configuration command procedure, you can specify a shadowed system
disk virtual unit as the satellite's system disk. The cluster configuration
command procedure then automatically sets the satellite's system
parameters SHADOW_SYS_DISK and SHADOW_SYS_UNIT for you. The values
of these parameters are transferred automatically to the system
parameter file VAXVMSSYS.PAR for VAX satellites and to ALPHAVMSSYS.PAR
for Alpha satellites. (See the OpenVMS Cluster Systems manual for more information about
using this command procedure.)
For DECnet--Plus commands, see the DECnet--Plus documentation.
DECnet Database Example of a Satellite Node shows the NCP
commands you should enter on a MOP server to display a satellite
DECnet database entry. Note that the load assist parameter displays
the shadow set virtual unit name that downline loads the satellite
node HIWAY1.
DECnet Database Example of a Satellite Node uses
an explicit virtual unit name. However, you might prefer to use
a logical name that translates to the virtual unit.
Example 4 DECnet Database Example of a Satellite Node
You may need to adjust the settings of the SHADOW_MBR_TMO
and SHADOW_MAX_COPY parameters on satellite nodes. These parameters
are not automatically set by the cluster configuration command procedure. See
Volume Shadowing Parameters for more information.
The cluster configuration command procedure automatically
enables shadowing on satellite nodes when you want to shadow the
system disk. If you do not want to shadow the system disk but need
to enable shadowing, you must do so manually after the cluster configuration
command procedure completes. Set shadowing parameters in the satellite
node's MODPARAMS.DAT file and execute AUTOGEN as described in
Volume Shadowing Parameters and in
Setting System Parameters.
Booting Satellite Nodes shows two
satellite nodes with shadowed system disk volumes located in an
OpenVMS Cluster system configuration. In this configuration, the
devices $254$DUA1 and $254$DUA2 make up a two-member shadow set.
The satellites HIWAY1 and BYWAY2 access shadow set members across
the Ethernet via the MSCP servers in the two boot nodes.
Figure 1 Booting Satellite Nodes
When a satellite node in
Booting Satellite Nodes is booted, the boot node (MOP server) downline loads
initial bootstrap code from the virtual unit DSA1. The boot node
points the satellite to use either $254$DUA1 or $254$DUA2 as a boot
device for the remainder of the boot process. Note
that the boot node must have the virtual unit mounted. The satellite
then forms the system disk shadow set locally according to the shadow
set membership information stored in the SCB on the boot device.
The following SHOW DEVICES command displays how the shadow
set appears after the satellite node HIWAY1 is booted. In this example,
the physical disk devices are accessed through the MSCP server node BTNODE.
$ SHOW DEVICES DSA1
Device Device Error Volume Free Trans Mnt
Name Status Count Label Blocks Count Cnt
DSA1: Mounted 0 MYVOLUME 181779 194 37
$254$DUA1:(BTNODE) ShadowSetMember 0 (member of DSA1:)
$254$DUA2:(BTNODE) ShadowSetMember 0 (member of DSA1:)
$