Dell SRDF Introduction

High availability

In other SRDF configurations, devices on the primary array are Read or Write accessible to the application host while devices on the additional arrays are Read Only or Write Disabled. However, in an SRDF high availability configuration:

• Devices on the additional array are Read/Write accessible to the application host.
• The application host can write to both sides of the device pair.
• The devices on the additional array assume the same external identity (such as geometry and device identifier) as the devices on the primary array.

This shared identity means that the devices appear to the application host as a single, virtual device across the two arrays. Using two devices improves the availability of the data that they contain. One device can become unavailable without impacting on the host application as the second device continues to operate.

Such a configuration, which is known as SRDF/Metro, can be deployed in a single, multipathed host environment, or in a clustered environment as this diagram shows:

High availability describes SRDF high availability and its system configurations in more detail.