If used incorrectly, however, virtualization technology can shoot you in the foot. Remember, virtualization isn't magic. It can't create CPU, memory, or disk IOPS out of thin air.
As you grow your virtualization infrastructure, it should be fairly easy to keep tabs on CPU and memory performance. Any virtualization hypervisor worth its salt will give you visibility into the headroom you have to work with. Disk performance, on the other hand, is tougher to track and more likely to get you into trouble as you push virtualization to its limits.
By way of example, let's say you have a hundred physical servers you'd like to virtualize. They're all essentially idling on three-year-old hardware and require 1GHz of CPU bandwidth, 1GB of memory, and 250 IOPS of transactional disk performance.
You might imagine that an eight-socket, six-core X5650 server with 128GB of RAM would be able to run this load comfortably. After all, you have more than 20 percent of CPU and memory overhead, right? Sure, but bear in mind that you're going to need the equivalent of about 140 15,000-rpm Fibre Channel or SAS disks attached to that server to be able to provide the transactional load you'll require. It's not just about compute performance.
Performance tip No. 9: To dedupe or not to dedupe
As your data grows exponentially, it's natural to seek out tools that curb the use of expensive storage capacity. One of the best such examples is data deduplication. Whether you're deduplicating in your backup and archiving tier or directly to primary storage, there are massive capacity benefits you can derive weeding out similar data and storing only what is unique.
Deduplication is great for the backup tier. Whether you implement it in your backup software or in an appliance such as a virtual tape library, you can potentially keep months of backups in a near-line state ready to restore at a moment's notice. That's a better deal than having to dig for tape every time you have a restore that's more than a day or two old.
Like most great ideas, however, deduplication has its drawbacks. Chief among these is that deduplication requires a lot of work. It should come as no surprise that NetApp, one of the few major SAN vendors to offer deduplication on primary storage, is also one of the few major SAN vendors to offer controller hardware performance upgrades through its Performance Acceleration Modules. Identifying and consolidating duplicated blocks on storage requires a lot of controller resources. In other words, saving capacity comes at a performance price.
Performance tip No. 10: Accelerate your backups
Backups are almost always slower than you'd like them to be, and troubleshooting backup performance problems is often more art than science. But there is one common problem that nearly every backup administrator faces at some point or another.