DEC-TA79+TA81-MagneticTapeSubsystems-1986

This document describes Digital's TA78 and TA81 magnetic tape subsystems, designed as shared resources with enhanced performance for VAXcluster Systems, connecting via HSC50 or HSC70 Servers.

Key Features and Benefits Common to Both:

• Shared Resources: Increase availability and redundancy within VAXclusters, reducing contention and offering cost savings compared to non-clustered systems.
• Enhanced Performance: Offload I/O overhead from CPUs to the HSC Storage Server via Digital Storage Architecture (DSA), significantly improving system throughput and backup times, especially with the HSC's Local Backup Utility.
• Data Integrity: Feature outstanding data integrity with read-after-write verification, automatic error detection, and correction (ECC/CRC) during operation.
• Flexibility: Support dual-density recording (1,600 bpi PE and 6,250 bpi GCR), making them suitable for data interchange, acquisition, and software loading, as well as backup.
• Ease of Use & Maintenance: Designed for high reliability, include built-in diagnostics, and offer investment protection through upgrade kits for existing TU78/TU81 systems.

Differentiating Features:

• TA78: The high-performance, top-of-the-line subsystem. It excels in applications requiring fast start/stop capabilities like journaling and transaction processing. A TA78 master unit can also support up to three TU78 slave tape transports.
• TA81: The economical mid-range choice, mechanically simpler due to its streaming tape technology, resulting in lower ownership and maintenance costs. It's ideal for sustained input/output tasks such as high-capacity disk backup and data archiving. While primarily streaming, it also supports a low-speed start/stop function.

In summary, both TA78 and TA81 provide robust, high-integrity tape solutions for VAXcluster environments, allowing users to choose the subsystem that best fits their performance, budget, and application-specific needs.