It's an odd juxtaposition. The Dell PowerEdge R715 sits in a rack just below a recently decommissioned 2U, two-socket server that cost about as much when it was new five years ago. The difference? The older server has a total of two CPU cores, one per processor. The R715 has 32 cores, running at the same clock speed. If that's not progress, I don't know what is.
The R715 has been around since February (see InfoWorld's review), so strictly speaking, it's not a new server version. What's new: the R715's twin 16-core AMD Opteron "Interlagos" CPUs and support for 1,600MHz DDR3 RAM. Best of all, existing R715 systems can be upgraded to support the new chips with nothing more than a BIOS update. Otherwise, Interlagos is a drop-in replacement for Magny-Cours.
Like Magny-Cours before it, Interlagos promises to bring unbeatable price-performance to heavily multithreaded workloads such as virtualization. It costs considerably less than its closest Intel counterparts and offers twice the cores of the leading Intel chip. However, Interlagos is based on a new core architecture that is not yet supported by a number of popular operating systems (more on that below).
AMD Opteron 6200: Big guns, new design
The AMD Opteron 6200-series Interlagos CPUs have 16 cores and 16 threads, each of which has a dedicated core. However, as the first Opteron based on AMD's new modular architecture, the Interlagos chip is built from eight Bulldozer modules. Each module, in turn, has two independent processors, but the FPU, fetch, decode, and execute units are shared. It's not quite the same as having 16 completely independent cores.
One casualty of the architecture changes is that several operating systems simply will not run on Interlagos by default. These include Windows Server 2003 prior to R2 SP2; RHEL 4.x, RHEL 5.0 through 5.6, and RHEL 6.0; Novell SLES 10 through SP3 and SLES 11; and any Linux variant running a 2.6.31 kernel or earlier. The latter group includes VMware ESX 3.5 and VMware ESX 4.0 through 4.1u1.
A number of other operating systems will run but won't take advantage of all the new capabilities. RHEL 6.1 and SLES 11 SP1 will take advantage of the AES-NI instructions, but not the AVX extensions or Turbo Core. Windows Server 2003 R2 SP2, Windows Server 2008 SP2, and VMware ESX 4.1u2 will run but won't take advantage of the new instructions or features.
Then there's the list of operating systems that will handle both the new features and the AES-NI instructions, such as VMware vSphere 5.0, Windows Server 2008 R2 SP1, and RHEL 6.2. These are only a few examples of operating systems with full support, and some of these OS versions are still in beta. It's important to know whether or not your core operating systems are supported on this chip before you make any purchasing decisions.
It's also important to note that a compatible hypervisor, such as VMware vSphere 5.0, will allow virtualized instances of incompatible operating systems -- such as RHEL 5.5 -- to run on an Interlagos box.
Dell PowerEdge R715: Interlagos edition
The Dell R715 is a 2U rack-mount server with redundant power supplies, four gigabit Ethernet ports, and a DRAC6 Express or Enterprise embedded management controller. With six 2.5-inch hot-swap drives on the front, it can support up to 6TB of raw storage, backed by Dell's PERC H200 or PERC H700 internal RAID controllers. There's a limit of 256GB of RAM, and for the moment, the 1,600MHz DDR3 RAM is limited to 4GB and 8GB DIMMs; 16GB DIMMs are expected to be available soon.