## About High-Availability Features

The system is designed to provide high levels of reliability, availability, and serviceability (RAS). All components in the system's data path are redundant so that the data path has no single point of failure. If one component fails, the system switches to the alternate component automatically. The following components have been designed for high-availability:

- Management interface cards ( MICs) - Two MICs share one IP address, operating in master/alternate master mode.
- Storage trays - The controller trays operate in master/alternate master mode in each array. In addition, the loop card (LPC) and cables each provide one path to devices in a tray. If the loop card fails, the data can be accessed through the cables.
- Hot spare drives - Hot spare drives are always powered up and available but are not part of the array's virtual disk. Two types of hot spare drives are available:

- Array hot spare - One or more disks are configured as part of a storage pool. The pool's array hot spare is available to all virtual disks in the array.
- Dedicated hot spare - A disk serves as a hot spare for a designated virtual disk.

A configuration that has dedicated hot spares in every storage tray and array hot spares in every pool supports high availability.

The system uses several mechanisms to recognize a hardware failure. When a component recognizes that it has failed or the management software detects a failure, the component is removed from active service and its functions are assigned to other components of the system. The system generates an error event and records it in log files located on the Storage Service Processor.

### Related Topics

- System Overview
- About the Sun StorEdge 6920 System