RPO Replication for TS7700 Disaster Recovery

Merle SadlerBy Merle Sadler

This blog is on the topic of the impact of zero Recovery Point Objective (RPO) for Mainframe Virtual Tape Replication focusing on the IBM TS7700 replication capability.

Have you ever thought about how much money you will need to save for retirement? I was talking with my financial advisor the other day and decided that whatever you think you need you should double. You can plan on having social security but if social security fails then retirement plans start to look not so rosy.

budget tradoffs for RTO and RPO

The same thing applies to computer systems. Customers spend a lot of time and money on Disk replication, reducing both RPO and RTO. But what if an application corrupts the data or a virus is uploaded? Corrupted or infected data is replicated just as easily as good data. This lends to making offline backup copies of disk files which also need to be replicated.

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What’s Using Up All My Tapes? – Using Tape Management Catalog Data

BrettBy Dave Heggen

tape management catalog

Most of the data processed for IntelliMagic Vision for z/OS Tape is performance, event or activity driven, obtained from SMF and the Virtual Tape Hardware. Did you know that in addition to the SMF and TS7700 BVIR data, IntelliMagic Vision could also process information from a Tape Management Catalog (TMC)? Having this type of data available and processing it correctly is critical to answering the question “What’s using up all my tapes?”.

We’re all set up and distributed scratch lists. This is a necessary (and generally manual) part of maintaining a current tape library. It does require participation for compliance. Expiration Dates, Catalog and Cycle management also have their place to automate the expiration end of the tape volume cycle. This blog is intended to address issues that neither compliance nor automation address.

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IBM TS7700 Replication – Is Your Data Safe? (Part 2 of 2)


By Burt Loper


One of the challenges in IT is getting your data replicated to a remote location for fail-over and data recovery if your main operations center is compromised. It is not sufficient to set up replication, you also have to watch closely whether your replication goals are met at all times.

Part 1 of this blog explored the various TS7700 replication modes. Part 2 explores how IntelliMagic Vision can be used to monitor the health of the TS7700 replication process.

TS7700 Replication Monitoring

The TS7700 keeps track of many performance statistics about its operation. A constant watch of these metrics is needed to make sure that performance and replication goals are being met. IntelliMagic Vision performs fully automated daily interpretation of all relevant performance statistics. It applies built-in intelligence about the hardware and workloads to rate the health of the clusters and flag exceptions in dashboards and charts. The enhanced metrics are put in a database that can also be used for ad-hoc reporting with easy-to-use graphical views. Continue reading

Does your Disaster Recovery Plan meet its objectives? Analyzing TS7700 Tape Replication (Part 1 of 2)


By Burt Loper


This blog is the first in a series of two blogs on the topic of Mainframe Virtual Tape Replication.

One of the challenges in IT is getting your data replicated to another location so that you have a recovery capability if your main operations center is compromised. IBM TS7700 Series Virtualization Engines support the copying of your tape data to other locations.

This article explores the various TS7700 replication modes.

TS7700 Terminology

The IBM TS7700 Virtualization Engine is commonly known as a cluster. When you connect two or more clusters together, that is called a grid or composite library. The information here applies to both the TS7740 model (which uses backend tape drives and cartridges to store tape data) as well as the TS7720 model (which uses a large disk cache to store tape data).

In a multi-cluster grid, the clusters are interconnected with each other via a set of 1 Gb or 10 Gb Ethernet links. The TS7700’s use TCP/IP communication protocols to communicate with each other and copy tape data from one cluster to another.

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IBM TS7700 Performance – What can you do if your Cache Hit Percent drops too low and affects your tape performance?


By Burt Loper

What can you do if some of your tape jobs seem to be running too long and you observe that your Cache Hit Percent for your TS7740 virtual tape system is low?

First, let’s define Cache Hit Percent.  When host systems mount a tape, there are 3 possibilities:

  1. A scratch mount – this is always a cache hit as long as the TS7700 fast ready categories are configured correctly.  These are called Fast Ready mounts by the TS7700.
  2. A specific mount where the volser being requested is already in the TS7700’s cache.  These are called Cache Read Hit mounts by the TS7700.
  3. A specific mount where the volser being requested is not in the TS7700’s cache.  These are called Cache Read Miss mounts by the TS7700.

The first two mount types usually result in very quick tape mount times on the order of 1-2 seconds.  The mount time for a Cache Read Miss mount is much longer since the data from the volser must be retrieved from a tape cartridge back into the cache before the host mount can complete.  Cache Hit Percent for an interval is the sum of the Fast Ready mounts and the Cache Read Hit mounts divided by the Total virtual mounts (i.e. Fast Ready + Cache Read Hit + Cache Read Miss).

So, a low Cache Hit Percent means that more tape mounts are encountering  longer mount times associated with a Cache Read Miss mount and may mean that jobs take longer.  A general rule of thumb is the Cache Hit Percent should be at least 80%, but greater than 90% is preferable.

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