IBM SG24-5360-00 manual Ramac Virtual Array, IXFP/SnapShot for VSE/ESA

2.2.1 RAMAC Virtual Array

The RVA′s virtual disk architecture enables performance improvement in batch processing. This new architecture, coupled with data compression and

self-tuning capabilities, improves disk capacity utilization. Data from all logical volumes is written across all the physical disks the array. Automatic load balancing across the volumes occurs as data is written to the array. Further, the ability of the RVA to dynamically configure additional volumes of various sizes eliminates volume contention and thereby reduces I/O bottlenecks.

In the RVA, space that has never been allocated or is allocated but unused takes up no capacity. Data set size can increase and new files can be created with minimal need to reorganize existing stored data. Users of traditional storage systems keep lots of available free space to avoid batch application failures, wasting valuable space and increasing storage costs. With the RVA it is not necessary to keep lots of free space to avoid out-of-space conditions.

2.2.2 IXFP/SnapShot for VSE/ESA

Based on the belief that the best I/O is no I/O, IXFP/SnapShot for VSE/ESA reduces online system outage by reducing the amount of elapsed time backups and copies need to complete. IXFP/SnapShot for VSE/ESA improves these aspects of batch processing:

∙Data backup

Data is backed up during batch processing for many different reasons. Copying data to protect against a hardware, software, or application failure in the computer center is considered an operational backup. The backup might be a complete copy of all data, or an incremental copy, that is, a backup of the changes made since the last backup.

Data backups can be taken between processing steps to protect against data loss if a subsequent job or step fails. These backups are called interim backups. In some data centers, interim backups are done with tapes.

Using SnapShot to replace the backup and/or copy operations speeds up processing. Tapes are no longer required, and interim backups are done more quickly. Additional interim backup points are now possible because of the instantaneous copy capability and reduced batch processing time. The interim backups are deleted after successful completion of the batch process.

In many cases the operational backups made are also used for disaster recovery. Many of the considerations for disaster recovery are also valid for operational backup. You can minimize the time for disaster backups using SnapShot, by making a SnapShot copy to disk. You can then restart online applications before making a tape backup of the SnapShot copy.

∙Data set reorganization

Data set reorganization is very often a time-consuming part of nightly batch processing. The REORG becomes important especially when it is part of the critical path of batch processing. Traditional reorganization procedures copy the affected VSAM key-sequenced data set (KSDS) into a sequential data set on tape or on another DASD. This activity takes a long time when large data sets are copied. SnapShot can dramatically reduce the run time when used in place of IDCAMS REPRO to copy the KSDS into a sequential data set on another DASD.

Chapter 2. RVA Benefits for VSE/ESA 9