Single-instance systems vs. multi-instance systems

Installing Hitachi Content Platform for Cloud Scale

Version
2.4.x
Audience
anonymous
Part Number
MK-HCPCS002-11

An HCP for cloud scale system can have a single instance or can have multiple instances (four or more).

Note: Every instance must meet RAM, CPU, and disk space minimums.

One instance

A single-instance system is useful for testing and demonstration purposes. It needs only a single server or virtual machine and can perform all product functionality.

However, a single-instance system has these drawbacks:

  • A single-instance system has a single point of failure. If the instance hardware fails, you lose access to the system.
  • With no additional instances, you cannot choose where to run services. All services run on the single instance.

Multiple instances

A multi-instance system is suitable for use in a production environment because it offers these advantages over a single-instance system:

  • You can control how services are distributed across the multiple instances, providing improved service redundancy, scale out, and availability.

    For information on services, see Services list.

  • A multi-instance system can survive instance outages. For example, with a four-instance system running the default distribution of services, the system can lose one instance and still remain available.
  • Performance is improved as work can be performed in parallel across instances.
  • You can add additional instances to the system at any time.
    Note: You cannot change a single-instance system into a production-ready multi-instance system by adding new instances. This is because you cannot add master instances. Master instances are special instances that run a particular set of HCP for cloud scale services. Single-instance systems have one master instance. Multi-instance systems have at least three.

    By adding additional instances to a single-instance system, your system still has only one master instance, meaning there is still a single point of failure for the essential services that only a master instance can run.

    For information about adding instances to an existing HCP for cloud scale system, see the HCP for cloud scale online help.

Four-instance system considerations

The minimum HCP for cloud scale configuration has four instances. Four-instance systems should have three master instances.

For information about master instances, see About master and worker instances.