Storage

Protecting and managing distributed data is a classic storage challenge for most environments. Distributed data is commonly perceived as being at remote locations, outside the data center, or not on a mainframe. Distributed storage includes network-based (LAN servers) storage file servers in a building, campus, or metropolitan area. Distributed storage supports a wide range of applications such as e-mail, database, e-commerce and more. With the proliferation of distributed and duplicated data, the complexity and cost to protect all this data is compounding proportionally. This article examines various techniques, including emerging trends and technologies, for accessing, protecting, and managing distributed data…

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DASD Analysis Methodology

My article in the June/July z/Journal, “The Value of Good DASD Response Time,” discussed DASD Response Time (RT) in the z/OS environment, identified its components, and illustrated the value of good RT. If RT isn’t good, then tuning or other remedial actions (such as a DASD hardware upgrade) is required. This article briefly recaps key points from the prior article, discusses how to identify symptoms of DASD tuning problems, and offers a case study that demonstrates an approach many performance analysts use to easily identify problems…

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Back in the early ’80s, converting those pesky tape-based JCL streams and application code seemed more hassle than it was worth. Then, Hierarchical Storage Management (HSM), augmented with automation, made you look at those JCL streams yet again. Then, along came a philosophy called Tape Mount Management, followed by virtual tape systems, all attempting to make better use of tape media, and improve wall clock time. You might have tried one or a combination of these offerings when they came into vogue, but you’re still fighting the plague…

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DFSMShsmis a component of the DFSMS/MVS family of products that provides facilities for managing data stored on MVS storage devices. A primary task of DFSMShsm is to ensure that space is available on your DASD volumes so you can allocate new data sets or extend existing ones. DFSMShsm ensures that backup copies of your data sets are available in case of corruption or unintentional deletion of data. It automates manual storage management tasks and improves DASD usage…

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Numerous articles and white papers have been written on the performance advantages of Fibre Connection (FICON) over Enterprise Systems Connection (ESCON). Clearly, FICON is a major improvement over ESCON; data centers that have migrated from ESCON to FICON have seen improved response times and performance. Yet, only an estimated 20 to 25 percent of existing ESCON customers have migrated to FICON. A major factor in delaying a migration to FICON is the initial cost of entry, including the purchase of new hardware and infrastructure. Another factor was the lack of native FICON storage devices when FICON was initially announced as generally available. This has led to many prospective FICON customers having to do “rolling upgrades” of storage devices, which has further increased the cost of migrating. Mainframe users find it difficult to recognize and quantify cost savings associated with eliminating some ESCON infrastructure and leveraging other existing ESCON hardware by attaching it to the FICON network. …

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In today’s 24x7 data center, one copy of a critical application volume isn’t enough. To run backup operations, load data warehouses, or test new versions of applications without disrupting the flow of information to users and applications, IT administrators must create multiple copies of primary production volumes…

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Once upon a time, a 3390 Model 3, with 2.8GB of storage capacity (3,339 cylinders of 15 tracks of 849,960 bytes), was a rather large disk. That time has long since passed. However, most S/390 and zSeries installations continue to use the venerable Model 3 as their basic storage system. Most zSeries Linux systems, therefore, inherit the Model 3. At sites running z/VM, they’ll usually get minidisks carved out of this for their use rather than entire dedicated devices. Because the Linux DASD driver uses, by default, a 4K block size, the formatted capacity of a 3390-3, in a form useful to Linux, is generally about 2.3GB…

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Mainframe managers today are struggling to craft a cost-effective strategy for business continuance, of which traditional disaster recovery is only one part. The broader mandate of business continuance, however, makes it a more complicated and potentially more expensive task than mainframe disaster recovery. This is forcing managers to explore a growing set of options, especially asynchronous replication, and to assemble the optimum mix of technologies to achieve the organization’s business continuance and disaster recovery goals in the most cost-effective way…

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