Checkpoint Service

NetPlane Core Services

 

 

In the case of asynchronous update option, one of the replicas is designated as the active replica. Data is always read from the active replica and there is no guarantee that all the other replicas contain identical data. A write call returns after updating the active replica.

In the case of synchronous update options, the call invoked to write to the replicas returns only when all replicas have been updated, i.e. either all replicas are updated or the call fails and no changes are made to the replicas.

The CPSv supports both collocated and non-collocated checkpoints. In case of checkpoints opened with collocated and asynchronous update option, it is up to the application to set a checkpoint to the active state. In all other cases the CPSv itself handles which checkpoint is currently active.

The Checkpoint Service defined by SAF does not support hot-standby. This means that the currently stand-by component is not notified of any changes made to the checkpoint. When the stand-by component gets active, it has to iterate through the respective checkpoint sections to get up-to-date. To overcome this drawback, the CPSv provides additional, non-SAF APIs which help to notify the stand-by component of changes and thus facilitate the implementation of a hot-stand-by.

2.5.2.2Architecture

The CPSv service consists of the following subparts:

zCheckpoint Director (CPD)

zCheckpoint Node Director (CPND)

zCheckpoint Agent (CPA)

2.5.2.2.1Checkpoint Director

The Checkpoint Director runs on the active system manager node. Its main tasks are:

zGenerating a unique ID for each new checkpoint created by applications

zMaintaining the list of nodes on which replicas of a particular checkpoint exist

zSelecting the Checkpoint Node Director (CPND) which oversees the active replica for each checkpoint

zCoordinating the creation and deletion of checkpoints

zMaintaining a repository for the CPSv policy and configuration-related information

There is an active and a stand-by CPD running respectively on the two system manager nodes. CPD uses the NCS Message based Checkpoint Service to keep the two synchronized and available for failover situations.

NetPlane Core Services Overview User’s Guide (6806800C08B)

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Motorola 6806800C08B manual Checkpoint Director, Checkpoint Service NetPlane Core Services
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6806800C08B specifications

The Motorola 68000 microprocessor, particularly the revision marked as 68000C08B, stands out as a seminal component in the evolution of computing technology. Introduced in 1979, the 68000 architecture laid the groundwork for many advanced systems, influencing a multitude of platforms, from personal computers to game consoles.

The Motorola 68000C08B features a 16-bit data bus and a 24-bit address bus, allowing for a memory addressing capability of up to 16 MB. This architecture was pioneering for its time, enabling more extensive and complex software applications than its predecessors. The C08 revision particularly emphasized optimizing power consumption while maintaining performance, making it ideal for embedded systems and portable devices.

One of the 68000's key characteristics is its unique register set, which allows for a versatile range of operations. It consists of 8 general-purpose data registers and 8 address registers. The architecture supports both integer and floating-point operations, thanks to an integrated instruction set that facilitates complex mathematical computations, crucial for applications in graphics and gaming.

In terms of performance, the 68000 processor operates at clock speeds ranging from 8 MHz to 16 MHz, depending on the specific variant. The instruction set architecture (ISA) is known for its orthogonality, meaning that most instructions can be used interchangeably across different registers. This design simplicity allows for efficient coding and faster execution times, a significant advantage for developers.

Another remarkable feature of the 68000C08B is its capability for multitasking and improved context switching. Its advanced memory management, combined with support for virtual memory in later implementations, catered to the needs of operating systems and real-time applications, making it suitable for both consumer electronics and industrial machinery.

The Motorola 68000 family also supports a variety of peripherals, enhancing its flexibility as a microcontroller. This compatibility allowed manufacturers to create diverse product lines, from keypads and mice to modems and hard drives.

In summary, the Motorola 68000C08B microprocessor not only advanced the landscape of computer technology in the late 20th century but also helped set the stage for future innovations through its architecture, performance capabilities, and versatility in numerous applications. Its legacy continues to influence modern computing paradigms, ensuring the 68000 remains an essential chapter in the history of microprocessors.
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