The Virtual Tape Paradox
Today, z/OS installations face fundamental questions regarding the management and future planning of offline storage resources. While robotic tape systems initially provided solutions for these problems when they were introduced more than a decade ago, they have become part of today's problem. Specifically, while the number of robotic tape subsystems continues to increase in most installations, the small tape problem (i.e., low cartridge utilization) continues to compromise the value of offline storage investments.
Virtual tape subsystems have been proposed as yet another solution to the small tape problem. While most of these subsystems incorporate service processors, buffer DASD, and tape robotics, other solutions have been proposed based on host software and large DASD buffers. These subsystems incorporate technologies ranging from SSA DASD to log-structured file schemes along with a variety of tape robotic schemes.
The performance claims made for virtual tape subsystems further complicate the decision process. As a potential buyer, you often find almost an order of magnitude difference in the performance characteristics of a prospective virtual tape subsystem when you compare the claims of the vendor, the critical observations made by competitors, and the informed opinions of industry pundits, many of whom simply estimate subsystem performance by talking to the vendors. As a result of these factors, many installations are making strategic offline storage decisions without a reliable basis for understanding the true capabilities of the new technologies.
The PAI/O Driver Solution
PAI/O Driver for Tape from Performance Associates is the solution to this dilemma. Our product is both technology independent and vendor independent, and it comprises four distinct parts:
An acquisition methodology,
A reporting service based on independent testing of tape and virtual tape subsystems,
Profiling software to characterize your virtual tape requirements, and
A software program which allows users to measure and verify virtual tape subsystem performance.
Installations can employ PAI/O Driver for Tape to help in the tape selection process, to aggressively negotiate acquisition agreements, or to verify performance clauses in acquisition contracts. It can:
Reduce the cost of acquiring new tape technology,
Limit the risks associated with the acquisition and introduction of new tape technologies, and
Support the specification and enforcement of the vendor's contractual obligations.
When you have PAI/O Driver for Tape, you can tell the vendors what you want and verify that you've gotten it!
The Acquisition Methodology
To maximize potential cost benefits and to minimize your risk during the acquisition process, it is essential that a request for proposal be technology independent and that effective performance assurances are included in your acquisition contract. Our PAI/O Driver acquisition methodology directs you in meeting these objectives. The methodology shows you how to acquire a new virtual tape subsystem which meets all of your specifications at the lowest cost. It shows you how to specify a technology independent request for proposal. Moreover, it describes the procedure for including an effective performance assurance clause in your acquisition contract.
Virtual Tape Subsystem Profiles
A library of profiles for the most current virtual tape subsystems is included with our user enterprise-licenses. An inventory of our profile library is maintained on our home page at www.perfassoc.com.
The Reporting Service
In contrast to marketing claims about virtual tape subsystem performance, the PAI/O Driver for Tape reporting service presents and interprets hard repeatable tape subsystem performance measurements. Rather than being a benchmark of a particular workload, PAI/O Driver for Tape employs a specifically designed standard engineering test series to explore the performance characteristics of any virtual tape subsystem over a wide variety of configuration alternatives and workload types.
While there is no single test which can provide an absolute evaluation of the suitability of a virtual tape subsystem for a specific workload or customer environment, each PAI/O Driver for Tape subsystem profile report provides your installation with reliable commentary and analysis. This is because it is based on hard measurement data, not unsubstantiated marketing claims or industry hearsay.
We at Performance Associates are committed to the continued measurement and analysis of new virtual tape subsystem offerings and the publication of our research reports to licensed user sites. While we will formally distribute new subsystem profiles to subscribers on a semiannual basis, we will make informal results available as soon as they are collected.
In the event that you have installed, or have access to, a subsystem which has not yet been analyzed, we will perform the analysis at our own expense.
PAI/O Driver for Tape is compatible with MVS/ESA 5.1 through the most current releases of z/OS and is Year 2000 compliant. It features a standard engineering test series and includes SAS® workload profiling software for the development of customer-specific performance verification tests.
Performance Associates Services
We can assist you in the measurement, analysis, and acquisition of new virtual tape subsystems or unique configurations. Being well versed in the specific requirements presented by state and federal acquisition regulations, we can help speed the acquisition process for government agencies and certify the performance of upgrades over the life of your contract.
Licensing and Additional Information
PAI/O Driver for Tape is an enterprise-licensed product. For additional information and license terms, please contact Performance Associates at:
Performance Associates, Inc.
P.O. Box 5080
Pagosa Springs, CO 81147-5080
Voice: (970) 731-DASD x104
Fax: (970) 731-1024