Stretch Brocade Fabric

Synopsis: Designs with best practices for a two-site data center disaster recovery solution using Brocade Fiber Channel ISL connections over extended distance.

Contents

Overview

The most common reason for extending a Fibre Channel (FC) storage area network (SAN) over extended distances is to safeguard critical business data and provide near-continuous access to applications and services in the event of a localized disaster. Designing a distance extension solution involves a number of considerations, both business and technical.

From the business perspective, applications and their data need to be classified by how critical they are for business operation, how often data must be backed up, and how quickly it needs to be recovered in the event of failure. Two key metrics are the Recovery Point Objective (RPO) and the Recovery Time Objective (RTO). The RPO is the time period between backup points and describes the acceptable loss of data after a failure has occurred. For example, if a remote backup occurs every day at midnight and a site failure occurs at 11 pm, changes to data made within the last 23 hours will be lost. RTO describes the time to restore the data after the disaster. RTO determines the maximum outage that can occur with an acceptable impact to the business.

From a technology perspective, there are several choices for the optical transport network and configuration options for the FC SAN when it is extended over distance. Applications with strict RTO and RPO require high-speed synchronous or near-synchronous replication between sites with application clustering over distance for immediate service recovery. Less critical applications may only require high-speed replication that could be asynchronous to meet the RPO/RTO metrics. Lower priority applications that don’t need immediate recovery after a failure can be restored from backup tapes from remote vaults.