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Mainframe Solutions

Virtual Tape: Still a Vital Component of Business Continuity in Mainframe Environments

by Dr.Steve.Guendert on ‎10-13-2015 07:48 AM (4,511 Views)

After the often repeated and always false rumors of the mainframe’s imminent demise, probably the next most egregiously false rumor is that tape and/or virtual tape is going away. We’ve all heard this and perhaps even seen some of the conference booth marketing hype. I visit countless large IBM mainframe installations around the world each year. Based on these meetings, I can safely say that the overwhelming majority of these organizations still view tape (physical and virtual) as an important component of their business continuity strategy and architecture. This includes the EMC Disk Library for Mainframe (DLm), the Oracle Virtual Storage Manager 6 (VSM6), Luminex Mainframe Virtual Tape (MVT), and the IBM Virtualization Engine TS7700 (IBM TS7700). All four vendors continue to enhance their virtual tape products. The remainder of this blog will focus on the IBM TS7700 Grid solution and a new network technology designed to enhance it. This new technology is known as IP Extension (IPEX).  Subsequent posts will discuss the application of the Brocade 7840 and IPEX to Oracle VSM6, EMC DLm and Luminex MVT.


IBM TS7700 Grid Basics

The technology of a prior generation produced the IBM Virtual Tape Server (VTS), which had a feature called Peer-to-Peer (PtP) VTS. PtP VTS was a multisite-capable business continuity and disaster recovery solution and was to tape what PtP Remote Copy (PPRC) was to Direct Access Storage Devices (DASDs). PtP VTS-to-VTS data transmission was originally done by Enterprise Systems Connection (IBM ESCON), then IBM FICON®, and finally Transmission Control Protocol/Internet Protocol (TCP/IP).

With the TS7700, the virtual tape controllers for the PtP VTS of the prior generation were eliminated. This change provided the potential for significant simplification in the infrastructure that is needed for a business continuity solution and for simplified management. Instead of FICON or ESCON, the connections between the TS7700 clusters use standard TCP/IP. Similar to the PtP VTS of the previous generation, with the new TS7700 Grid configuration, data can be replicated between the clusters, based on the customer’s established policies. Any data can be accessed through any of the TS7700 clusters, regardless of which system the data is on, if the grid contains at least one available copy.


As a business continuity solution for high availability and disaster recovery, multiple TS7700 clusters are interconnected by using standard Ethernet connections. Local and geographically separated connections are supported to provide a great amount of flexibility to address customer needs. This IP network for data replication between TS7700 clusters is more commonly known as a TS7700 Grid. A TS7700 Grid refers to 2 to 6 physically separate TS7700 clusters that are connected to each other with a customer-supplied IP network. The TCP/IP infrastructure that connects a TS7700 Grid is known as the grid network. The grid configuration is used to form a high-availability disaster recovery solution and to provide metro and remote logical volume replication. The clusters in a TS7700 Grid can be, but do not need to be, geographically dispersed. In a multiple-cluster grid configuration, two TS7700 clusters are often located within 100 kilometers (km) of each other. The remaining clusters can be more than 1,000 km away. This solution provides a highly available and redundant regional solution. It also provides a remote disaster recovery solution outside of the region.


The TS7700 Grid configuration introduces new flexibility for designing business continuity solutions. Peer-to-peer communication capability is integrated into the base architecture and design. No special hardware is required to interconnect the TS7700s and the interconnection interface is changed to standard IP networking. If configured for high availability, host connectivity to the virtual device addresses in two or more TS7700s is required to maintain access to data, if one of the TS7700s fails. If the TS7700s are at different sites, channel extension equipment such as the IBM SAN42B-R is required to extend the host connections.


With the TS7700 Grid, data is replicated and stored in a remote location to support truly continuous uptime. The IBM TS7700 includes multiple modes of synchronous and asynchronous replication. Replication modes can be assigned to data volumes by using the IBM Data Facility Storage Management Subsystem (DFSMS) policy. This policy provides flexibility in implementing business continuity solutions, so that organizations can simplify their storage environments and optimize storage utilization. This functionality is similar to IBM Metro Mirror and Global Mirror with advanced copy services support for IBM z Systems customers.

The TS7700 Grid is a robust business continuity and IT resilience solution. By using the TS7700 Grid, organizations can move beyond the inadequacies of on-site backup (disk-to-disk or disk-to-tape) that cannot protect against regional (nonlocal) natural or human-induced disasters. By using the TS7700 Grid, data can be created and accessed remotely through the grid network. Many TS7700 Grid configurations rely on this remote access to further increase the importance of the TCP/IP fabric.


With increased storage flexibility, an organization can adapt quickly and dynamically to changing business environments. Switching production to a peer TS7700 can be accomplished in a few seconds with minimal operator skills. With a TS7700 Grid solution, z Systems customers can eliminate planned and unplanned downtime. This approach can potentially save thousands of dollars in lost time and business and can address today’s stringent government and institutional data protection regulations.


A TS7700 Grid network requires nonstop predictable performance with components that have “five-9s” availability. A TS7700 Grid network must be designed with highly efficient components that minimize operating costs. These components must also be highly scalable, to support business and data growth and application needs and to help accelerate the deployment of new technologies. This new white paper on the TS7700 Grid and Brocade 7840 (IBM SAN42B-R) IP Extension technology will discuss how that technology further enhances the TS7700 grid network.  Watch for weekly blog posts over the next month that will focus more in depth on the IPEX technology topics in this white paper.