What about cloud and online backup? What are the pros and cons of using a managed service for replication?
Cloud backup is certainly an area of interest, and if the goal is simply to get a secondary copy of data offsite, then cloud offerings certainly are attractively priced options. The question is, how do you plan to use those remote copies of data? If cloud is being used for backup, recovery of individual files may be easy enough, but recovery of full volumes of data may take time depending on your bandwidth. Also, from a disaster recovery standpoint, you need to determine if you're going to need to copy everything back to a location to make it useful, and this could also take a long time. Some cloud vendors are making use of caching techniques to streamline and improve performance. For example, one new product that's in beta, from a new company called Cloud Array, claims to offer a virtual storage array that can connect into your favorite cloud service and offers built-in replication between local and cloud storage much in the same way that a host-based replication would offer in your private environment. The virtual array sits inside a virtual machine and VMware environment and provides much of the same functionality that you would see in a storage array. So there is an iSCSI interface out to hosts and on the back end you can have your own local storage, or you can connect to any number of cloud storage vendors.
