Not too long ago, disaster recovery (DR) was an exercise in logistics involving hundreds of tapes, elaborate transportation schemes and numerous personnel assignments. But no matter how well a company was prepared, it was almost inevitable that the sheer complexity of the plan meant something would fall through the cracks. A single missing tape could cripple a recovery.
Tape has its place in data protection, including disaster recovery, but not for the mission-critical applications that a company relies on to maintain business as usual -- or as close to usual as possible. Today's business environment is almost a cliché: 24/7 operations, global reach, interwoven networks of suppliers and customers, and a sense that a day in the docks could spell doom for a company. With that kind of urgency, and recovery time objectives (RTOs) that are barely a blink of the eye, tape just doesn't cut it.
Data replication is the obvious alternative to tape recoveries. Typical replication setups called for array-to-array replication, which required duplicating the production site configuration at the recovery site. To say the least, duplicating primary storage for recovery purposes often meant an extraordinary expense to ensure business continuity. Other approaches, like host-based replication, are cheaper to implement, but they come at a cost, as well as with greater maintenance and administration.
In the last few years, storage managers have received some relief on the budgetary and administrative sides of the disaster recovery and replication equation. Dozens of newer data replication tools sidestep the constraints of earlier generations of replicators, principally by allowing data to be replicated between different storage configurations.
On the server side of the shop, virtualization has radically redefined disaster recovery by breaking the one-to-one, physical server-to-physical server setup that had been required for a recovery site. Now, a single server hosting many virtual servers may serve as the disaster recovery mechanism to support multiple primary servers. And with virtual server setups at both primary and recovery sites, the flexibility is almost endless. Fortunately, newer replication products are up to the task and can match the resiliency and flexibility of virtualized server environments.
That's not to suggest that data replication for disaster recovery is necessarily a lot easier to implement. There are still a lot of decisions to make, like when to use synchronous vs. asynchronous replication, and the appropriate types of recovery site storage that won't bust budgets but will still be up to the task of maintaining business processes at an acceptable level.
In this guide
on disaster recovery replication, you'll get a good look at the various replication
alternatives, where they might be most effectively deployed, and how server and storage
virtualization can be best exploited. Replication may never entirely eliminate tape from DR
scenarios, but it has certainly provided a faster and more reliable alternative.
-- Rich Castagna, Editorial Director of TechTarget's Storage Media Group
A LOOK INSIDE THIS DISASTER RECOVERY AND REPLICATION GUIDE:
Replication alternatives: Data replication as a means of data protection has seen continuous and increasing adoption since it first emerged in storage systems after the first World Trade Center bombing in 1993. Over time, it has evolved into an indispensable component of disaster recovery, as well as for operational backup for applications that require shorter recovery point objectives (RPOs) and recovery RTOs than what traditional tape backups can offer. Firms are also adopting data replication for remote- and branch-office data protection; in a hub-and-spoke architecture, branch-office data can be replicated back to central data centers, thus eliminating unwieldy tape-based backup procedures at the branch sites.
Disaster recovery and replication FAQ: With the increasing availability of data replication products, many are turning to this technology as part of a disaster recovery strategy to address tighter RTOs. W. Curtis Preston discusses replication in the DR space in this article.
Data replication tools: Wading through replication products is tough enough, but determining which products best fit your system is even harder. We provide readers with a list of available replication products and how they differ from each other.
Disk array-based data replication -- the pros and cons: There are three main types of data replication: application based, host based and array based. Learn the differences between the three technologies, how to get started with array-based replication and find out about available products.
This was first published in July 2010