High Availability Tailored for SMBs

摘要

System availability embodies several concepts. Simply put, these are the ability for a system to maintain function even when system maintenance tasks are underway or if some components are malfunctioning, and the ability to recover as quickly as possible after a system goes down - for whatever reason. High Availability (HA) is the practice of avoiding such sources of unplanned downtime by keeping any system available more than 99 percent of the time. Typically, an HA system uses the remote journaling capability in OS/400 and i5/OS, which keeps data on one or more servers (or partitions on the same server) synchronous by sending transactions and changes to a backup server. If the primary server becomes unavailable, the backup takes over processing and, if necessary, can be the data source for restoring the primary server later. Until just the past few years, HA systems were generally regarded as expensive undertakings that only the largest enterprises should consider. But electronic commerce, supply chains, and 24/7 operations at many small-to-medium businesses (SMBs) are making disaster recovery and HA solutions a widespread SMB business requirement.