When a zVT configuration is installed at a customer site, from an operating system point of view, the zVTs are simply groups of tape drives. From an Operations standpoint, the zVT presents several challenges which zVT Control Center (ZCC) has been designed to address:

Tape Migration

To streamline a tape migration project, ZCC includes the ZVTCLONE migration utility. Exact copies of tapes are created in a zVT library using the same volume name and device type. The system catalogs and tape management systems are not affected – only the “location” of the tape is changed. If an SMS Tape library is involved in the migration project, the application also manages records in the Tape Configuration Database (TCDB). To aid migration throughput, the ZVTCLONE application can perform up to 99 concurrent tape copy tasks to migrate tapes into a zVT library.

Command Interface

Many installations segregate the TCP/IP network used by the zVT to connect to the back-end storage device; therefore, the operations and support staff have limited access to the web interface used to configure the zVT. However, ZCC can interface to zVT nodes through the channel interface, independent of any network impediments. For command processing, the product temporarily reserves a tape device in a zVT for command execution. As soon as the command completes, the device is released. ZCC can issue zVT commands from:

• operator consoles
• batch jobs
• TSO/ISPF

Monitoring Interface

The product can monitor the zVT event log using SNMP. Event triggers can be used to log messages to a data set, SMF records, and/or send messages to operations via the operator console, email or text messages.

Allocation Interface

The ZCC zVT Allocation interface can be used to control device allocation. If a requested tape resides in a zVT library, only the library devices are eligible for the allocation request. When non-library tapes are requested, ZVTALLOC removes the zVT tape devices from the eligible device list. The interface can also perform unit affinity splits if DD statements try to share the same device, but volumes between the DDs are inside/outside the zVT. Lastly, ZCC identifies the condition where a multi-volume tape dataset uses volumes inside/outside the zVT. In this case, the product uses installation defined rules to handle the conditions. By default, the rules issue a warning message and then terminates the job.

Load Balancing

Mainframes have historically been very good at optimizing I/O performance on channel connections. However, installations that have multi-zVT configurations present serious optimization challenges. Due to the number of emulated devices on each zVT controller, and the inability to access the I/O workload on the network connections between the zVTs and backend storage, the network connections for some zVTs can become I/O saturated while others are left idle. This problem is especially prevalent in JES3 installations and zVT configurations that have 1000+ tape devices configured.

The zVT Control Center (ZCC) uses device selection technology developed for the DTS DASD products to enable load balancing across zVTs. ZCC influences the device selection during Allocation. Allocation builds an Eligible Device List (EDL) for the tape request, and ZCC uses a load balancing selection algorithm to spread the tape requests among the zVTs.

Dynamic Scratch Synonyms

ZCC can be used to dynamically assign scratch synonyms to jobs during job initiation. When the ZVTSCR component is started, the product dynamically installs an IGXMSGEX exit – no SMP/E work or IPL is required. Once started, the ZVTRULES member can be used to create policy rules to set the scratch synonym for scratch requests made by jobs. The ZVTRULES have access to the current job and step information, as well as the related security fields. This allows rules to use job names, accounting information, or RACF user/group fields to assign a scratch synonym. The ZCC IGXMSGEX exit provides rules tracing facilities, rule refresh support using a console command, and dynamic start and shutdown capabilities.

Scratch Exit

When a tape management system (TMS) changes the status of a tape to “scratch”, the TMS system calls an exit that can be used by ZCC to intercept the scratch request. ZCC can immediately notify the zVT that the tape is now scratch. This allows the zVT to have the scratch status synched real-time with the tape management system. The currently supported environments: OAM, IBM RMM, and CA-1.

ZCC  provides a wide range of benefits that will ultimately allow installations to more effectively install, implement and manage the zVT. This will be accomplished by providing:

Robust Command and Monitoring Interface

• Modern, efficient and familiar interface
• ISPF/TSO, z/OS system console and batch jobs
• Capture zVT events via an SNMP

Advanced Intelligent Device Selection

• Advanced Allocation Control ensures proper device selection
• NO JCL changes required
• Eliminates the need for OAM or SMS management of zVT tapes
• Provides policies for scratch, multivolume and unit-affinity requests

Efficient Transition via Automated Migration Manager

• Automates and manages the migration of tape libraries
• Unique ‘cloning’ technology for maximum accuracy & effectiveness
• NO updates to TMS required
• Provides simplicity to complex issues

Load Balancing Optimization

• Optimizes performance for multi-node zVTs
• Automated via a device selection algorithm

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