Buyer's Guide: VMware Replication

Virtualization has a lot of benefits. You save power, make better use of existing hardware—you know the spiel. But it also comes with some increased risks, because you're putting your eggs into fewer baskets. If you have a hardware failure or virus infection in a host, you also have problems for all the virtual machines (VMs) running on the host. That means that in a virtual environment, you not only need to make sure that all your VMs are getting backed up properly, you also have to be certain and that losing one host doesn't mean your entire IT environment is out of commission.

There are many choices for products to help you replicate your VMware environment, so start with the buyer's guide table accompanying this article to get an idea of what's out there. Take a thorough inventory of what you have and what you need before you start shopping so you know you're headed in the right direction.

Basic backup hardware considerations, including storage capacity and performance, are as important in a virtual environment as anywhere. However you're replicating and wherever you're replicating to, make sure your drives can handle the data. If you're going for more than simple backups, you also have to make sure that your network and server hardware is up to the task. If you want a replication system with automatic failover, make sure you actually have the capacity to fail over your VMs. If you don't have the computing power, you could have one host crash, then when its VMs failover to the next, that host could becomes bogged down and unusable.

Licensing can be one of the trickier aspects of virtualization, and licensing a VMware replication product is no exception. In the sampling of products in the accompanying table there are products licensed on a per-server or host basis, per VM, per CPU socket, and per TB of storage. Before committing to a product, make sure to know the terms under which you're getting the product and what you'll need to pay if your needs change.

Inventory your hosts and VMs carefully so that the product you choose covers all of the OSs you use. Another consideration is whether the product will help you backup a mixed hypervisor environment—Microsoft's Hyper-V is seeing use in many IT test environments and is also moving into more and more production environments. If you're planning on using more than one hypervisor, or if you'd just like to leave the option open, don't forget to include that factor in your decision.

Cloud replication is a feature you should consider carefully. Offsite storage can save your data in case of an emergency, and knowing that your data is regularly being stored with your service provider can provide a lot of peace of mind. On the other hand, cloud storage isn't the best option for every environment. Local storage is very inexpensive these days, and cloud storage space can sometimes be substantially more expensive. You might also be located somewhere with limited bandwidth. Cloud storage can also raise serious legal questions, especially when data would be stored in a country other than the one where you're located. If the country where you're storing your data has laws allowing its government to seize the data—as the U.S. does—you could face problems with your own government. Many industries also regulate where you can store your data, so you might have to get your company's legal department involved with this decision.

Even a casual glance at this month's buyer's guide table will show you that you have a lot of choices in this area, and the products have big differences between them. There are also many different licensing models and price levels. A good replication setup can keep your computers running after a disaster, but a bad one will only lull you into a false sense of security, making a disaster that much worse.