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- George Crump, Storage Switzerland
Meeting an organization's disaster recovery challenges requires addressing problems from several angles based on specific recovery point and recovery time objectives. Today's tight RTO and RPO expectations mean almost no data gets lost and no downtime.
To meet those expectations, businesses must move beyond backup and consider a data replication strategy. Modern replication products offer more than just a rapid disaster recovery copy of data, though. They can help with cloud migration, using the cloud as a DR site and even solving copy data challenges.
Replication software comes in two forms. One is integrated into a storage system, and the other is bought separately. Both have their strengths and weaknesses.
An integrated data replication strategy
The integrated form of replication has a few advantages. It's often bundled at no charge or is relatively inexpensive. Of course, nothing in life is really free. The customer pays extra for the storage hardware in order to get the "free" software. In addition, at-scale, storage-based replication is relatively easy to manage. Most storage system replication works at a volume level, so one job replicates the entire volume, even if there are a thousand virtual machines on it. And finally, storage system-based replication is often backup-controlled, meaning the replication job can be integrated and managed by backup software.
There are, however, problems with a storage system-based data replication strategy. First, it's specific to that storage system. Consequently, since most data centers use multiple storage systems from different vendors, they must also manage multiple replication products. Second, the advantage of replicating entire volumes can be a disadvantage, because some data centers may not want to replicate every application on a volume. Third, most storage system replication inadequately supports the cloud.
IT typically installs stand-alone replication software on each host it's protecting or implements it into the cluster in a hypervisor environment. Flexibility is among software-based replication's advantages. The same software can replicate from any hardware platform to any other hardware platform, letting IT mix and match source and target storage devices. The second advantage is that software-based replication can be more granular about what's replicated and how frequently replication occurs. And the third advantage is that most software-based replication offers excellent cloud support.
At a minimum, the cloud is used as a DR target for data, but it's also used as an entire disaster recovery site, not just a copy. This means there can be instantiate virtual machines, using cloud compute in addition to cloud storage. Some approaches go further with cloud support, allowing replication across multiple clouds or from the cloud back to the original data center.
The primary downside of a stand-alone data replication strategy is it must be purchased, because it isn't bundled with storage hardware. Its granularity also means dozens, if not hundreds of jobs, must be managed, although several stand-alone data replication products have added the ability to group jobs by type. Finally, there isn't wide support from backup software vendors for these products, so any integration is a manual process, requiring custom scripts.
Modern replication features
Modern replication software should support the cloud and support it well. This requirement draws a line of suspicion around storage systems with built-in replication, because cloud support is generally so weak. Replication software should have the ability to replicate data to any cloud and use that cloud to keep a DR copy of that data. It should also let IT start up application instances in the cloud, potentially completely replacing an organization's DR site. Last, the software should support multi-cloud replication to ensure both on-premises and cloud-based applications are protected.
Another feature to look for in modern replication is integration into data protection software. This capability can take two forms: The software can manage the replication process on the storage system, or the data protection software could provide replication. Several leading data protection products can manage snapshots and replication functions on other vendors' storage systems. Doing so eliminates some of the concern around running several different storage system replication products.
Data protection software that integrates replication can either be traditional backup software with an added replication function or traditional replication software with a file history capability, potentially eliminating the need for backup software. It's important for IT to make sure the capabilities of any combined product meets all backup and replication needs.
How to make the replication decision
The increased expectation of rapid recovery with almost no data loss is something everyone in IT will have to address. While backup software has improved significantly, tight RPOs and RTOs mean most organizations will need replication as well. The pros and cons of both an integrated and stand-alone data replication strategy hinge on the environment in which they're deployed.
Each IT shop must decide which type of replication best meets its current needs. At the same time, IT planners must figure out how that new data replication product will integrate with existing storage hardware and future initiatives like the cloud.