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A Virtual Tape Primer

Virtual Tape


The word “virtual” is used to describe something that doesn’t physically exist, but is made by software to appear to do so. Virtual tape is an enterprise data storage solution that imitates physical tape drives by storing information on disk drives.

In reality, the data is saved in tape format but is actually stored on another storage device. The cloud can certainly be involved for off-site versus on-site applications of the technology. With numerous advances in virtual tape along with its ease of conversion, the technology is poised to be around for a long time as it combines tape, flash and software-defined storage while still remaining cost effective. This article examines the technology behind virtual tape storage and explains why you might want to use it.

Why Use Virtual Tape Storage?

Using virtual tape storage offers many advantages, including but not limited to:

  • Ease of management. Because the format of physical tape is the same, very little needs to be changed. This allows applications to simply be redirected to the virtual tape media for writing.
  • Portability. It’s easy to move data via electronic methods. Actually, it’s quite similar to transmitting disk storage files, but it’s done in tape format.
  • Scalability. Scalability isn’t typically an issue in virtual tape storage, as more clusters can be easily added on.

With downtime averaging upwards of $9,000 per minute, according to TechTarget (bit.ly/2OsCfli), organizations are looking to find cost-effective methodologies to help with that problem. Organizations are adopting business continuity and recovery strategies by utilizing various storage technologies to address operational risks.

Using virtual tape storage allows businesses to benefit from virtualization of physical tape and achieve their goals of solid, long-term data retention at a lower cost. Various virtual tape storage configurations provide high availability and rapid disaster recovery (DR). Another plus is the ability to perform end-to-end data encryption for security and to meet regulatory guidelines.

With virtual tape, data can be electronically transmitted to a DR site and replicated, creating a very smooth DR process. Data can be selected to push certain types of data out to the DR site because only specific portions of tape need to be replicated to the DR environment.

Creating a Virtual Tape Strategy

Choosing the correct strategy for virtual tape isn’t always obvious. With shrinking backup windows, poor reliability of backup systems, performance issues or escalating costs, selecting a new strategy can be daunting. When looking at data protection strategies, virtual tape is on the continuum from conventional tape, continuous data protection and asynchronous/synchronous replication to three node DR. Most strategies will rely on tape for the final storage and archiving solution.

When considering a strategy for virtual tape, ask yourself the following questions:

  • What is the projected budget?
  • Who will support the solution?
  • What is the timing of the backup window?
  • How can existing investments in virtual tape be utilized?
  • How much data loss is acceptable?
  • What is the ROI?

Knowing the answers to these questions will help you formulate an acceptable virtual tape strategy. All ramifications of utilizing the technology must be fully understood—including topics such as, “How will deduplication and encryption impact recovery times?” and “How will compliance affect the virtual tape strategy?” Think about how to keep the auditors happy.

How to Measure Virtual Tape Performance

When discussing the metrics of virtual tape, it helps to think about DASD measurements. The use of SMF and RMF records can yield a lot of information on exactly how well your virtual tape is performing. The measurements for virtual tape mirror DASD measurements in quite a few ways. The virtual tape is really just the tape format written to disk so a lot of the DASD metrics do indeed apply.

To make your virtual tape work at its peak, you should always ensure that your host processes are working well and your interfaces with the host and virtual tape environments are set up correctly.

Capacity planners love to focus in on Tape Volume Cache (TVC) rated in hourly utilization in gigabytes. An average of active gigabytes rated against the maximum of TVC size and an 85 percent maximum threshold shows a good picture of virtual tape performance in the environment.

Another important consideration of virtual tape metrics lies in the area of recovery point objective (RPO). RPO is the maximum targeted time period in which data might be lost from an IT service due to major issues with production. Shops often strive to hit zero RPO on virtual tape for perfect business continuity, and the ability to utilize virtual tape is spot on when it comes to this objective.

Virtual tape can significantly impact RPO. Data from virtual tape storage can be electronically moved over a network to another site, just like with DASD. A variety of reporting mechanisms show exactly how much data is located at off-site locations.

An Applied Use of Virtual Tape Storage

The manufacturing and banking industries have been heavy users of virtual tape in the past, and that still rings true today. Virtual tape storage performance capabilities match up well with disk technologies and have a true 4:1 compression capability, making it a solid solution to consider.

One large manufacturer (bit.ly/2MopDeN), for example, was facing the problem of a soon-to-be unsupported tape infrastructure, and fixing this issue proved to be a challenge. The company was very much committed to mainframes but it needed relief to better its OPEX versus CAPEX approach.

Enter the virtual tape system. After completing a modernization study for tape that reviewed its current tape environment, a proposition was pursued to replace the company’s current tape infrastructure with virtual tape storage. The company was able to perform the migration effort in five weeks.

The move to virtual tape storage brought the company several benefits, including:

  • The end of management concerns on pending issues with the old tape environment
  • The ability to stay within a given budget for the new tape replacement to virtual tape storage
  • Improved backup times
  • Removal of expensive tape handling and storage costs

Walking the Path of Virtual Tape

One of the biggest advantages of virtual tape over real tape is that it can bring a quick ROI, which is a good thing when it comes to managing your data center expenses. If you haven’t already done so, you should take a look at an open storage-based virtual tape system as it can provide cost savings, the ability to scale and increased reliability.

Because virtual tape is really a disk technology, data can be electronically transferred, boding well for DR applications. The software-only virtual tape systems are the least expensive. Performance, when compared to real tape, is better, especially when you consider the elimination of rewind and mount times by the operation staff.

Virtual tape takes on a tried and tested storage methodology, making it better without losing the original format. The original format is tape, but with virtual tape systems, it’s now in a disk format. You owe it to yourself to better understand the path that virtual tape can provide in your data center.

Patrick Stanard is a mainframe integration architect for IBM Global Technology Services. He’s a 35 year professional in the industry spanning roles as a systems programmer, developer, manager, business unit executive, affiliate faculty member and director of operations. He has a Bachelor of Science in CIS from Saginaw Valley State University and an MBA from Michigan State University.


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