Last week I took a look at the first three factors to consider when choosing a replication software product. This week I wanted to finish my thoughts around that subject and discuss the final four factors that should be part of any evaluation of replication software.
The first three factors as I discussed last week were:
- Continuous versus scheduled replication
- Efficiency of data transfer
- Block versus file
Here are the final four factors that every organization should consider when evaluating any replication software solution:
- Replication configuration flexibility. Organizations are getting more dispersed and more complex all of the time. Common topologies that may be supported include 1 to 1, N into 1, and 1 to N replication, each of which has advantages depending on the problem being addressed. Some products support only one-way replication, while others may support bi-directional replication.
Multiple different types of storage and operating systems may need to be supported as well. Array-based replication generally only works between storage arrays from the same vendor, while host, application, and appliance-based replication can generally support heterogeneous storage but may impose operating system or application lock-in. This puts the onus on organizations to find the right product for their environment.
- Overhead. Every replication software product is going to consume resources (memory and CPU specifically) as it does the replication. The issue that organizations need to address is where they want to place that load.
While the answer has historically been on the server or storage array since they have often had unused cycles to spare, as organizations increasingly move towards virtualized environments, excess CPU and memory on these systems are harder to come by.
Appliance-based replication can offer some advantages in high growth environments because of its low overhead, scalability, flexibility, and ability to support heterogeneous environments.
- Creation of recovery points. Replication and data protection are becoming almost inextricably linked as more organizations want to leverage replication for not just disaster recovery and high availability but their day-to-day data protection needs as well. This may include fast application recoveries or using the replicated data as the source for backups to tape.
However to perform these tasks the replication software has to be application-aware so it can support the application-consistent recovery options necessary to provide the fast, more reliable recovery capabilities as well as the ability to offload backups as desired from productions servers.
- Storage consumption. In the same way that all replication software products do not use network bandwidth efficiently, they also do not all use storage space efficiently. This especially comes into play when organizations start to use advanced features available on some replication software products such as continuous data protection.
In these implementations of replication software, all changes are kept for days, weeks or even months depending on the settings. This can consume much more storage capacity than what is in production unless the replication software has some mechanism to efficiently manage the replicated data.
For CDP products in particular, a nice feature to look for that can help reduce storage requirements is a feature called “sparse retention windows” that allow administrators to set policies that establish different levels of data retention granularity as data ages.
Organizations should not view it as a requirement that a single replication software product possess all seven of these attributes in order to consider it appropriate for use in their environment. However, the more of these features and options that the replication software product possesses, the more flexible it will be and the more likely it is that the replication software will meet whatever needs your organization has now or in the future.
Part 1 – 7 Considerations when Choosing a Replication Software Product