CA1 CopyCat virtual to virtual tape compaction

book

Article ID: 141554

calendar_today

Updated On:

Products

CA 1 Tape Management CA 1 Tape Management - Copycat Utility CA 1 Tape Management - Add-On Options

Issue/Introduction

The Virtual tape library consists of a dell/emc Disk Library for Mainframe (DLM) with a dell/emc Data Domain as the backup storage.

Currently  CopyCat 'FileCopy' is used to stack datasets on virtual tapes onto a Real 3590 for disaster recovery. 
A process of eliminating the Real 3590 tape drives is done, but the dataset's virtual tapes continue to be stacked onto another virtual tape.

Writing the datasets from virtual tapes to a real 3590 cartridge (both virtual and real tapes are defined as 10Gb) results in 1 real tape cartridge, writing from virtual to virtual will create  9 virtual tapes to stack the same data.

How can this be explained ?

Environment

Release : 12.0

Component : CA 1 Tape Management

Resolution

If the virtual-output-device actually has compaction disabled (as EMC has indicated) – then no compaction will be performed.

Copycat itself does NOT perform the compaction. Copycat simply allocates the output device requesting the output device perform the compression or not. So, even though we asked the device to compress – no compression was done by the device. Because the de-duplication/compression performed by Data Domain is way in the back-ground (way after the write has been performed); even the device does not believe that any compression was performed.