Secure Systems Data Mirroring

ClearPath OS 2200 offers you a number of availability solutions to ensure that data is still available to your applications and your users – even if access to a file or disk is disrupted. Whether a disruption is caused by a deliberate malicious action or an unintended hardware, software or human failure, your business-critical applications are still available. And your end users are completely unaware that anything has happened!

Choose from three methods of data mirroring. They all provide enhanced recoverability for the business-critical data on your ClearPath OS 2200 system.

Unit Duplexing

Unit duplexing works at the device level. This kind of host-based data mirroring not only eliminates the potential for data loss when a mass storage device fails. It also supports the continuation of system operations – even if the failing disk contains essential operating system information!

With OS 2200 unit duplexing, each disk can have an associated mirror disk. When a disk is unit duplexed, a write operation writes data to both disks and a read operation can read from either disk. Performance is improved by splitting the reads. This kind of mirroring is completely transparent to applications running on the OS 2200 host.

Compared to commodity RAID 1 hardware, OS 2200 unit duplexing gives you greater resiliency due to more complete path redundancy. You can put the mirror device on a separate channel… in a separate cabinet… with a separate power supply… in a separate location… and across a fireproof divider. Or even at the end of a fibre trunk 10 kilometers or more away.

Transaction Processing File Duplexing

Transaction processing file duplexing works at the file level. With this method your transaction processing applications can use special files that are optimized for transaction processing speed. And, to reduce vulnerability to mass storage failures, these files can be duplexed at the file level. A duplexed transaction processing file consists of two mass storage file copies (legs) of the same data. All writes are written to both legs. Reads can occur from either leg, providing improved performance.

Like unit duplexing, transaction processing file duplexing is transparent to your application software. And, it allows the application to continue running if one of the duplexed file legs fails. The damaged leg can even be repaired without compromising availability of the file. This allows great flexibility in file leg placement, including keeping one leg in memory for enhanced performance.

EMC Mirroring

Using disk subsystems from EMC in your ClearPath Plus configuration can give you even more protection against data unavailability. You can use EMC disk mirroring and remote data mirroring either independently or in conjunction with unit duplexing or transaction processing file duplexing.