TPF Controls for SRDF
by Alan Sadowsky

EMC Enterprise Storage™ helps you realize your most aggressive business goals through intelligent information sharing, management, and protection. Achieving those goals is what we call experiencing The EMC Effect™. Symmetrix® Remote Data Facility (SRDF™) helps you achieve The EMC Effect by providing you with complete business continuance capability in the event of a data center disaster, and during planned events such as daily backups, database loads and refreshes, application testing, scheduled maintenance, and data center migrations or consolidations.

SRDF is the only solution providing this facility simultaneously to Mainframe, UNIX®, Windows NT®, and AS/400® systems. This online, host-independent, mirrored data storage solution duplicates your production site data on one or more physically separate target Symmetrix 3000 or 5000 systems. Systems can be across the room, across the globe, or anywhere in-between. Wherever their location, SRDF business continuance enables you to realize 24x7 revenue generation and customer service capabilities for increased competitive advantage.

With the introduction of TPF Controls for SRDF, EMC will provide a robust TPF Operations interface to manage SRDF’s configuration and command processing directly from the TPF Prime CRAS console. Complete control of SRDF will be available to the TPF Operator via conventional Z-messages to initiate and monitor all of SRDF’s features.

SRDF's implementation and maintenance are easy and cost-effective. No special application coding is required and no CPU overhead is incurred. SRDF functions independently from the TPF host processor.

Set-up and installation parameters of the SRDF function are accomplished through the Symmetrix integrated service processor and through TPF Z-commands from the TPF Prime CRAS console.

SRDF for TPF - Managing the Expected and the Unexpected

Disaster Recovery
The typical recovery routine involves customized software and complex procedures. Offsite media – usually using comparatively slow tape technology – must be either electronically transmitted or physically shipped to the recovery site. This is then followed by time-consuming restores of your Capture and Exception Recording tapes. With SRDF for TPF, business operations are resumed much faster than with the conventional TPF restore solution. Simply stated, SRDF for TPF allows users to restart rather than recover their operational systems.

Eliminating the "Race to Sunrise"
Standard practice is to conduct regularly scheduled (usually daily) TPF Captures. With today's global enterprises, this practice has become anything but routine. TPF databases are larger, backup windows are smaller, and any impact on production system cycles costs revenue or service loss.

SRDF for TPF eliminates the race to sunrise while allowing your business operations to run continuously. Scheduled backup operations, data warehouse loading, or new application testing is performed from the target Symmetrix data while normal operations are continuously running on the source Symmetrix. All the while, your data can be safely protected, available, and expanding its earning power. For many businesses, the SRDF payback is measured in just days.

Data Migration
Because SRDF for TPF enables you to migrate data between sites quickly and non-disruptively, it can be used to support consolidation of data centers and reallocation of site workloads. It alleviates the usual lengthy outages and the need to transport physical media. Your IS staff can manage data migration in real time using SRDF for TPF software while applications remain online.

Scheduled Maintenance
SRDF for TPF also enables business operations to continue during scheduled site maintenance, such as operating system upgrades, host processor upgrades, and environmental disruptions. After processing is switched to the remote site, normal operations continue using the remote copy of synchronized application data.

Disaster Recovery Testing
You can test disaster recovery plans without manually intensive recovery drills, complex procedures, and business interruptions. Your IS staff can simply switch to the remote site at any time – testing can be performed during normal business operations. For businesses serving global markets, ensuring the highest level of data availability – with no downtime – is especially critical.

SRDF for TPF - Solutions to Meet Your Specific Needs

SRDF for TPF is a high-performance solution. It provides full mirroring of data between source and target systems. A single SRDF-configured Symmetrix can serve as the backup for up to 16 local or remote Symmetrix systems. At both the source and target sites, either Mirroring (RAID 1), RAID-S, or an intermix of both can be enabled within Symmetrix systems.

Quick and easy recovery from unplanned outages.

SRDF for TPF copies all user-specified data from a source Symmetrix system to a target Symmetrix. Your IS staff can quickly switch over from source to target when data center operations are disrupted. When the disruption at the primary site has been rectified, the communication link can be re-established. SRDF will automatically resynchronize the data between the sites, and normal operations can resume.

SRDF connectivity supports varying geographic requirements.

EMC offers several SRDF connectivity implementations to meet the specific geographic requirements of your business continuance solution. The ESCON®-based campus solution provides mirroring operations for target Symmetrix systems located from 10 feet to 66 kilometers from your source data center.

For contingency sites farther removed geographically, SRDF FarPoint™ software supports mirroring across all SRDF-supported telecommunications links, including T1/E1, T3/E3 and ATM.

SRDF FarPoint significantly increases performance through optimization of the communication line resulting in a much more cost-effective solution and, in some instances, allowing the same level of performance with fewer lines.

Multi-hop capability makes long-distance mirroring more affordable.

Another time- and cost-saving feature of SRDF is its multi-hop capability. Multi-hop enables SRDF users to mirror only data that has changed since the last update onto a Symmetrix system in a third location. Utilizing EMC TimeFinder™, this feature is ideal for cost-effectively mirroring data long-distance. By copying only the changed tracks, less bandwidth is consumed, performance is enhanced, and transmission times are shorter. Multi-hop mirroring to the third site can take place during off-peak times over lower cost transmission lines. Recurrent monthly line costs can be dramatically reduced, quickly recouping the investment in a third Symmetrix system.

SRDF for TPF Supports Multiple Modes of Operation

Synchronous Mode

Synchronous Mode provides real-time mirroring of data between the source Symmetrix and the target Symmetrix system. Data is written simultaneously to the cache of both systems – in real time – before the application I/O is completed, ensuring the highest possible data availability.

Semi-Synchronous Mode

Semi-Synchronous Mode writes data to the source system, completes the I/O, and then synchronizes the data with the target system. Since the I/O is completed prior to synchronizing data with the target system, this mode provides an added performance advantage. A second write will not be accepted on a volume until the target has been synchronized.

Adaptive Copy Mode

Adaptive Copy Mode transfers data from the source volumes to the remote volumes without waiting for an acknowledgment. This is recommended for transferring large amounts of data, such as during data center migrations or consolidations. All modes can co-exist simultaneously on Symmetrix, allowing application of the most appropriate mode to individual data volumes based on specific requirements.

The Winning Combination

When you combine the powerful features and functionality of EMC’s TimeFinder for TPF, and SRDF for TPF, you have an unbeatable suite of software solutions at your command. The critical issues of database backup and integrity become much more manageable. Disaster recovery procedures are greatly simplified, and overall system availability is dramatically improved. Couple these products with your existing console automation platforms, and the benefits of these business continuance solutions become even more evident.

If you would like additional information on SRDF for TPF, or would like to discuss how TPF Controls for SRDF can make your TPF installation more secure and productive, please contact your local EMC representative.