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Introduction

This section describes how to configure a DSSI cluster in CHARON-VAX for Windows.

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General description

The DSSI storage subsystem for the CHARON VAX 4000 106, 108, 700 and 705 models is based on the emulation of "SHAC" host adapters. Routing of SCS cluster information among the emulated "SHAC" host adapters of multiple nodes is done via separate TCP/IP links.

The DSSI storage subsystem is functionally emulated and operates at a much higher rate of throughput than the original hardware. Connections to the physical DSSI hardware is neither possible nor planned for future releases.

The current version of DSSI emulation for CHARON-VAX supports up to 3 VAX nodes in a virtual DSSI cluster and handles a maximum cluster size of 8 nodes. A single virtual DSSI network supports up to 256 storage elements.

For more details on a DSSI configuration follow this link.

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Configuration steps

To create a CHARON-VAX DSSI cluster, the following elements must be configured:

"SHAC" host adapter
"HSD50" storage controller

DSSI hardware topology is emulated by establishing TCP/IP channels between the emulated SHAC host adapters of each CHARON-VAX system. The emulated HSD50 storage controllers are then connected to every SHAC host adapter in the virtual DSSI network.

Cluster operation requires (virtual) disks that are simultaneously accessible by all CHARON-VAX nodes involved. This can be implemented for instance by using a properly configured iSCSI initiator / target structure or a fiber channel storage back-end. Disks on a multiport SCSI switch are not acceptable, as a SCSI switch does not provide true simultaneous access to multiple nodes.

It is advisable to start any field test with implementing the cluster examples provided below

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Example 1: Dual node DSSI cluster with 4 shared disks

To setup two emulated VAX 4000 Model 108 nodes, we need two host machines, preferably running the same version of Windows.

Assume that these host systems have network host names CASTOR and POLLUX in the host TCP/IP network.

The following are CHARON-VAX configuration files for the emulated VAX 4000 Model 108 nodes running on CASTOR and POLLUX:

CASTOR node

...

set PAA port[2]=11012 host[2]=”pollux:11021”

load HSD50 DISKS dssi_host=PAA dssi_node_id=3

set DISKS scs_system_id=3238746238 mscp_allocation_class=1

set DISKS container[0]="\\DiskServer\Share\dua0-rz24-vms-v6.2.vdisk" set DISKS container[1]="\\DiskServer\Share\dua1-rz24-vms-v6.2.vdisk"
set DISKS container[2]="\\DiskServer\Share\dua2-rz24-vms-v6.2.vdisk"
set DISKS container[3]="\\DiskServer\Share\dua3-rz24-vms-v6.2.vdisk" ...

POLLUX node

...

set PAA port[1]=11021 host[1]=”castor:11012”

load HSD50 DISKS dssi_host=PAA dssi_node_id=3

set DISKS scs_system_id=3238746238 mscp_allocation_class=1

set DISKS container[0]="\\DiskServer\Share\dua0-rz24-vms-v6.2.vdisk"
set DISKS container[1]="\\DiskServer\Share\dua1-rz24-vms-v6.2.vdisk"
set DISKS container[2]="\\DiskServer\Share\dua2-rz24-vms-v6.2.vdisk"
set DISKS container[3]="\\DiskServer\Share\dua3-rz24-vms-v6.2.vdisk"
...

Let's review both configurations step-by-step.

The first line of both configuration files establishes parameters for the preloaded "PAA" SHAC host adapter. Only 2 parameters of SHAC are important for us in this situation:

Parameter

Description

port

An integer value that specifies the TCP/IP port number on which an emulated SHAC host adapter listens for connections from another emulated SHAC host adapter.

Possible port values range from 1024 through 32767.

host

A string value that specifies the TCP/IP host name (and optional TCP/IP port number) to connect to another emulated SHAC host adapter.

The syntax for the string is “host-name[:port-no]” with possible values for "port-no" in the range from 1024 through 32767.

Thus, CASTOR connects to POLLUX's port 11021 and listens for POLLUX's connection on port 11012, POLLUX connects to CASTOR's port 11012 and listens for CASTOR's connection on port 11021

The second and third lines of both configuration files are for loading "DISKS", HSD50 storage controllers and its parametrization:

Parameter	Description
dssi_host	A string value that specifies the instance name of the emulated SHAC host adapter serving the virtual DSSI network. If this value is not set, CHARON-VAX tries to locate the host adapter automatically. This automatic lookup works only if the CHARON-VAX configuration has exactly one instance of the emulated SHAC host adapter.
dssi_node_id	An integer value that specifies the address of an emulated HSD50 storage controller on a virtual DSSI network. Possible values range from 0 through 7 (initially set to 0).
scs_system_id	A string value that specifies the SCSNODENAME of the emulated HSD50 storage controller. The string can consist of up to 10 characters. Possible characters are uppercase letters: A through Z and integers.
mscp_allocation_class	An integer value that specifies the ALLOCLASS of an emulated HSD50 storage controller. Possible values are from 0 through 255 (initially set to 0).

In both configuration files, the names of the emulated HSD50 storage controller "DISKS" must be identical. Not following this rule can cause data corruption on the (virtual) disks.

The last lines demonstrate mapping "DISKS" HSD50 storage controller to disk images, shared between both hosts. A "container" parameter is used for this purpose. This example assumes that all disk images are accessible from both host machines via Microsoft share or some other realization. It is also possible to create a network drive and use it in the CHARON-VAX configuration files abobe.

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Example 2: Triple node DSSI cluster with multiple iSCSI disks

In this example we assume that all three host systems have an iSCSI initiator and are connected to a common iSCSI server. The iSCSI disk server provides 8 virtual disks with R/W access on all hosts. These disks are configured as "\\.\PhysicalDrive0" to "\\.\PhysicalDrive7" on each of the host machines.

The storage configuration must be identical on all three nodes. It is recommended to describe the storage structure in a separate configuration file to be included in each CHARON-VAX configuration file with the use of the "include" instruction (name of the configuration file set to "disksets.cfg" in this example) and store it on a common network share ("\\DiskServer\Share"):

load HSD50 DISKS1 dssi_host=PAA dssi_node_id=4

set DISKS1 scs_system_id=3238746238 mscp_allocation_class=1

set DISKS1 container[1]="\\.\PhysicalDrive0"
set DISKS1 container[2]="\\.\PhysicalDrive1"
set DISKS1 container[3]="\\.\PhysicalDrive2"
set DISKS1 container[4]="\\.\PhysicalDrive3"

load HSD50 DISKS2 dssi_host=PAA dssi_node_id=5

set DISKS2 scs_system_id=1256412654 mscp_allocation_class=2

set DISKS2 container[5]="\\.\PhysicalDrive4"
set DISKS2 container[6]="\\.\PhysicalDrive5"
set DISKS2 container[7]="\\.\PhysicalDrive6"
set DISKS2 container[8]="\\.\PhysicalDrive7"

CHARON-VAX configuration file for the emulated VAX 4000 Model 108 node running on HOST001 is as follows:

...

set PAA port[2]=11012 host[2]=”host002:11021”
set PAA port[3]=11013 host[3]=”host003:11031

include \\DiskServer\Share\disksets.cfg
...

CHARON-VAX configuration file for the emulated VAX 4000 Model 108 node running on HOST002 is as follows:

... set PAA port[1]=11021 host[1]=”host001:11012”
set PAA port[3]=11023 host[3]=”host003:11032”

include \\DiskServer\Share\disksets.cfg ...

CHARON-VAX configuration file for the emulated VAX 4000 Model 108 node running on HOST003 is as follows:

... set PAA port[1]=11031 host[1]=”host001:11013”
set PAA port[2]=11032 host[2]=”host002:11023”

include \\DiskServer\Share\disksets.cfg
...

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