database would be corrupted and would have to be recovered from image copies and log data. In all cases notification of this miss must be known at secondary. When that happens for hundreds of volumes, without a clear notification of status of impacted secondary volumes, recovery can be extremely long. For more information on this topic, please refer to RAMAC Virtual Array: Implementing Peer-to-Peer Remote Copy, SG24-5338.

Figure 29 on page 97 shows time-sequenced I/O writes in a synchronous remote copy environment.

The Need for Time-Consistency

Many examples where the start of one write is time dependent on the completion of a previous write

Data base & log

 

 

 

S

Catalogs, VTOCs

P

(1)

Log update

Index & data components

LOG

(3)

Mark DB

LOG

Time sequence could be

 

update

 

exposed in remote copy

 

complete

 

To be managed through

P

(2) DB update

S

PPRC Critical attribute

DB

DB

 

Automation / Freeze function

 

 

 

Figure 29. Time Sequenced I/Os

9.5.4.2 Geographically Dispersed Parallel Sysplex

Currently some System/390 platform users have set up a sysplex over multiple sites for availability, capacity, and/or workload balancing reasons. However, these configurations provide reduced continuous application availability because, if a disaster occurs at the site where the data resides, the surviving portion of the sysplex will be down until lengthy data recovery actions can be completed. Moreover, data recovery can be expected to be incomplete and may lag actual production status by up to 24 hours.

A geographically dispersed parallel sysplex (GDPS) is a multisite availability solution that merges sysplex and remote copy technologies. GDPS provides an integrated disaster survival capability that addresses the system, the network, and the data parts of an application environment.

The primary objective of GDPS is to minimize application outages that would result from a site failure by ensuring that, no matter what the failure scenario is at the failing site, data in the surviving site is consistent and is therefore a valid base for a quick application restart. An installation-defined policy determines whether the switch will occur with limited loss or no loss of data.

In the event of a site failure (including disasters), the surviving site will continue to function and absorb the work of the failed site. In the event of a planned site outage, the workload executing in the site undergoing a planned outage will be quiesced and restarted at the other site. Current experience indicates that for large operational sites a planned switch from one site to the other takes less than 60 minutes (including networking), and site unplanned outage recovery takes less than 45 minutes. Only a single keystroke is required to invoke a GDPS action.

Disk Environment Overview

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IBM 5695-DF1, 5655-DB2 manual Need for Time-Consistency, Geographically Dispersed Parallel Sysplex
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5695-DF1, 5655-DB2 specifications

IBM 5655-DB2 and 5695-DF1 are significant components within the IBM software ecosystem, predominantly focusing on data management and integration solutions. These offerings cater primarily to enterprise environments that require robust database management systems and associated frameworks to maintain and manipulate data efficiently.

IBM 5655-DB2 is a well-known relational database management system (RDBMS) that excels in managing large volumes of structured data. Its architecture is designed to support high availability, scalability, and performance, crucial for businesses operating in today’s data-driven world. Some of its main features include advanced indexing capabilities, support for complex queries, and dynamic workload management. Additionally, it provides strong concurrency controls, which enable multiple users to access and manipulate data simultaneously without compromising data integrity.

One of the key characteristics of DB2 is its support for various data types, including JSON and XML, making it versatile for modern applications that generate data in diverse formats. It also features robust security mechanisms to protect sensitive data, aligning with compliance standards across industries. Integration with analytics tools further allows businesses to derive insights from their data, enhancing decision-making processes.

On the other hand, IBM 5695-DF1, also known as the InfoSphere DataStage, is a powerful data integration tool that facilitates the extraction, transformation, and loading (ETL) of data from various sources to target systems. It empowers organizations to streamline their data flows, ensuring that clean, consistent information is available for analysis and operational use. Key features of 5695-DF1 include a user-friendly graphical interface that enhances developer productivity and a rich set of connectors for numerous data sources, enabling seamless data integration.

DataStage also supports real-time data integration, allowing businesses to keep their data synchronized across multiple platforms. Its parallel processing capabilities dedicatedly optimize performance, enabling organizations to handle vast datasets efficiently. It incorporates data quality tools that help in validating and cleansing data before it is used for decision-making processes.

Both IBM 5655-DB2 and 5695-DF1 are part of a broader strategy to accommodate the evolving landscape of data management. Businesses leverage these technologies to enhance their data architectures, fostering agility and competitive advantage in their respective markets. Their integration capabilities, along with a focus on security and scalability, position them as vital assets in modern enterprise environments. Whether managing critical data within a database or ensuring seamless data flow across systems, these IBM offerings provide a comprehensive approach to handling complex data challenges.
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