CHARON-VAX for Windows DSSI cluster

Table of Contents

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:

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.

Steps to configure DSSI cluster:

1. Set unique ID for SHAC controller of each node

   Configuration	IDs of SHAC is set using console (and stored in ROM file, so make sure the ROM file is specified in configuration file) in the following way: >>>sho dssi_id DSSI_ID Bus 0/A = 1 DSSI_ID Bus 1/B = 1 >>>set dssi_id 0 2 >>>set dssi_id 1 2
   Description	Note that value of "dssi_id" must be unique for each SHAC instances and HSD50 controllers must not use them; for example if 0 and 1 is used as SHAC ID of different VAX nodes the HDS50 controller instance cannot use ID 0 and 1.

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2. Configure preloaded SHAC adapters PAA

   Configuration	set PAA port[<ID of the node to connect to>]=<port to receive connection from the node specified by ID> host[<ID of the node to connect to>]="<connected node host>:<connected node port>" Example: set PAA port[2]=11012 host[2]="pollux:11021" In this example a VAX node SHAC adapter connects to a node "pollux" (having ID=2) to its port 11021 and expects connection from it on the port 11012.
   Description	The second step is to interconnect SHAC adapters of different nodes. Use ID of the nodes as a reference for interconnections as it is shown in the example at left. Detailed meaning of the parameters is explained in "Example 1" section below

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3. Load HSD50 adapter

   Configuration

   load HSD50 <instance name> dssi_host=<SHAC instance> dssi_node_id=<HSD50 node ID> Example: load HSD50 DISKS dssi_host=PAA dssi_node_id=3 In this example HSD50 controller instance "DISKS" is loaded, connected to "PAA" SHAC controller and assigned with ID 3.

   Description

   Load HSD50 instance, assign ID for it and connect it to "PAA" SHAC adapter. For each member of cluster an identical definition of HSD50 controllers must be loaded. It is convenient to introduce a specific include configuration file containing the same configuration commands as it is shown in "Example 2" section below. Note that <HSD50 node ID> parameter must be unique for each SHAC and HSD50 instances; for example if 0 and 1 are used as IDs for nodes (see the Step 1) the HDS50 instance cannot use 0 or 1, but it can be set to 3, for example.

    

    

4. Set SCS system ID and allocation class

   Configuration

   set <HSD50 instance name> scs_system_id=<SCS ID> mscp_allocation_class=<allocation class> Example: set DISKS scs_system_id=3238746238 mscp_allocation_class=1 In this example HSD50 instance "DISKS" (configured at the previous step) is assigned with SCS ID "3238746238" and MSCP allocation class 1.

   Description

   Set SCS system ID and the MSCP allocation class. These setting must be the same for all HSD50 controllers loaded!   Note that the MSCP allocation class must be different from the allocation class of the VAX node (excuding some special cases when they can be the same - please refer to OpenVMS Guides on Clusters configuration for more details). For nodes it is set using MODPARAMS.DAT and AUTOGEN Refer to OpenVMS User's Guides for details

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5. Configure mapping to the system resources

   Configuration

   set <HSD50 instance name> container[<unit number>] = <mapping> Example: set DISKS container[0]="\\DiskServer\Share\dua0-rz24-vms-v6.2.vdisk" In this example the Unit 0 of the HSD50 controller instance "DISKS" is mapped to some disk image, located in some shared directory on disk server.

   Description

   The final step is specifying HSD50 mapping to the system resources. Since the disks should be distributed between different VAX nodes they should be located as disk images on some shared space or - alternatively - CHARON host should use such mechanism as iSCSI to address the common disks on some disk storage (they appear locally as "\\.\PhysicalDrive<N>"). See the sections below for different examples of the mapping.

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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"
... 

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