SureStore E Disk Array XP256 Business Copy XP and/or Continuous Access XP in an HP 3000 Environment

by Walt McCullough
Commercial Systems Division

Product Descriptions

Business Copy is an XP256 feature that allows for copy on demand of selected disk volumes. These volumes should be grouped as User Volumes, an MPE/iX term. These copied disks can then be split from their masters and presented to another HP 3000 machine for off-loading operations such as backup or application testing.

Business Copy volumes are managed from the internal XP256 PC or from a PC configured as the Remote Control PC.

The software used to manage Business Copy volumes is not currently available to execute directly from the HP 3000 but requires the separate PC to function.

Continuous Access is the feature that allows the XP256 to continuously maintain a copy of a selected number of disk volumes on another XP256 disk cabinet, located locally or remotely.

This feature is somewhat similar to Business Copy in that off-loading backup operations or application testing can be performed. The added value is that the user can use this feature to maintain a complete working set of data that could be used on the remote computer in the event of a catastrophic site outage at the primary location.

The software used to manage Continuous Access volumes is not currently available to execute directly from the HP 3000 but requires the separate PC to function.

Environment

Business Copy and Continuous Access is supported on MPE/iX release 5.5 with PPT07 and patch MPEKXL9 and MPEKXT8. It is also supported on MPE/iX release 6.0 with patch MPEKXL9 and MPEKXT8. For more information on patches and versions, please contact your support engineer.

Basic Operation

Business Copy and Continuous Access have virtually the same procedures for setup. System A will "own" data located on a primary user volume set. A running copy of this data will be maintained on a Business Copy of the volume set.

At a customer defined time, the user will VSCLOSE the primary user volume set and then split the primary user volume set from the Business Copy volume set.

After the split is complete, the user can then VSOPEN the primary user volume set onto System A and continue operations. System B can now VSOPEN the split off Business Copy volume set and proceed with its operations.

Figure 4-1 Basic Setup of Business Copy

System A Procedures

Setup System A

The first time setup requirements are as follows:

Create the Logical Unit Numbers (LUNs) and paths you will use on the XP256 and then using Sysgen or IOCONFIG create the LDEVs associated with the paths and LUNs. Make sure to use HPDARRAY as the ID type. We use the LDEV 60 through 62 for our examples. Test that MPE/iX recognizes the new LDEVs by either rebooting and running ODE Mapper or if you used IOCONFIG to issue the commands, use DSTAT ALL.

(MPE/iX Prompt):dstat all
  LDEV-TYPE    STATUS      VOLUME (VOLUME SET - GEN)
  ----------   --------    --------------------------
  60-OPEN-3    UNKNOWN
  61-OPEN-3    UNKNOWN
  62-OPEN-3    UNKNOWN   (MPE/iX Prompt):

Now create the User Volume Set that will be used to off-load processing. The volume set name for this example is PRODUCTION_DATA. Use the VOLUTIL utility program to create the user volume set named PRODUCTION_DATA. Once the volume set is created, VSCLOSE and then VSOPEN the volume set before proceeding onward.

Issue the DSTAT ALL command and the following should appear:

(MPE/iX Prompt):dstat all
  LDEV-TYPE    STATUS      VOLUME (VOLUME SET - GEN)
----------   --------    --------------------------
60-OPEN-3     MASTER      MEMBER1         (PRODUCTION_DATA-0)
61-OPEN-3     MEMBER      MEMBER2         (PRODUCTION_DATA-0)
62-OPEN-3     MEMBER      MEMBER3         (PRODUCTION_DATA-0)

Next, create the directory and accounting structure on the system that will use the User Volume. Be sure to remember to use the proper syntax and parameters ONVS and HOMEVS when creating the groups. You are now ready to restore or create the files that will reside on the user volume set PRODUCTION_DATA. From the Remote Control PC, configure the LUNs and paths for the Business Copy volumes and start the copy operation. This takes about 1 GB per minute depending on your configuration. Once this operation has completed, you may proceed. At this point you should have a system configured with a user volume set name PRODUCTION_DATA and a directory and accounting structure that is accessible from System B. You should also have a copy of this volume set maintained by Business Copy. To access the files and directories when this volume set is "moved" over to System B, you need to have the identical directory and accounting structure on System B that is already on System A.
BULDACCT
To access those files on the Business Copy volumes you must first create the accounts and groups on System B, that reference the directory structure located on the user volume. Re-issue the NEWACCT and NEWGROUP commands on System B or use BULDACCT to create a job stream that will create the directory for you.
Execute the buldacct utility program and for this example three accounts exist on the PRODUCTION_DATA volume set. SALESDB, ORDERDB and STOCKDB.
```
:RUN BULDACCT.PUB.SYS;INFO="SALESDB,ORDERDB,STOCKDB%VSACCT=PRODUCTION_DATA"
```
This will create 2 files BULDJOB1 and BULDJOB2. These files create the directory structure and re-create the UDC linkages. Store these files off and restore them to System B. (DSCOPY can also be used)

System B Procedures

Either re-issue the NEWACCT commands that pertain to creating the accounts on the system volume set and only those NEWGROUP commands that you used the parameter HOMEVS or restore the BULDJOB1 and BULDJOB2 files onto System B and stream those jobs.

From Sysgen or IOCONFIG issue the commands to configure the LDEVs of the Business Copy volumes. Be sure that the copy has completed. If you used Sysgen to configure the volumes you will need to reboot the system. If IOCONFIG was used, then it will try to mount the volumes as you add the LDEVs.

Once the volumes are configured and the directory structures are intact, issue the dstat all command.

(MPE/iX Prompt):dstat all
  LDEV-TYPE    STATUS      VOLUME (VOLUME SET - GEN)
  ----------   --------    --------------------------
  60-OPEN-3     LONER-RO    MEMBER1         (PRODUCTION_DATA-0)
  61-OPEN-3     LONER       MEMBER2         (PRODUCTION_DATA-0)
  62-OPEN-3     LONER       MEMBER3         (PRODUCTION_DATA-0)

The master volume should say LONER-RO, which means that it is closed and access is defined as Read-Only. MPE/iX will not let you mount a Read-Only disk because it is not supported on MPE/iX. The Read-Only attribute is set by the XP256 while it is active copy mode.

Business Copy Procedures

On System A

VSCLOSE PRODUCTION_DATA;NOW: This will quiesce I/Os to the volume set and flush all files and data structures resident to that volume set to disk. Within the Remote Control PC make sure that the primary and Business Copy disks are in sync and then split the primary volumes from the Business Copy volumes. (After the split you may VSOPEN the PRODUCTION_DATA volume set on System A and continue operations)

On System B

After the primary volumes have been split from the Business Copy you can issue the VSOPEN PRODUCTION_DATA command on System B and start operations.

When operations are completed, VSCLOSE PRODUCTION_DATA;NOW and from the Remote Control PC re-establish the primary and Business Copy mode. There is no need to log off users from System A to re-establish Business Copy.

Continuous Access

The diagram below describes the use of both Continuous Access and Business Copy to provide both disaster recovery and off loading of work done by the remote data center.

Figure 4-2 Using Both Business Copy and Continuous Access

The goal is to always maintain a link to the primary volume set through Continuous Access and use a separate set of disks that are maintained by Business Copy for planned events like work off-loading.

The process is almost the same as that of Business Copy. First quiesce I/O and log users off the PRODUCTION_DATA volume set by issuing the VSCLOSE;NOW command on System A. Then when all data has been moved to the remote XP256 only then do you split the Business Copy volumes from the Continuous Access volumes on the remote XP256.

Only when the Business Copy volumes are split on the remote XP256 can System B VSOPEN its copy of the PRODUCTION_DATA volume set.