Dell PowerEdge servers primed for virtualization
PowerEdge R805 and R905 boast VM-friendly features, raise bar for HP and IBM
A peek inside
The systems are based on AMD Opteron processors running at 2.5GHz. The AMD processors, curiously, run consistently better on virtualization benchmarks than their Intel counterparts. The difference is small (a few percentage points) but consistent. Although the exact reasons are unclear, Dell attributes the boost to better performance of the floating-point operations used in most benchmarks. However, I suspect that the superior AMD memory management is a greater contributor. We'll know more on this point when we see the results of benchmarking VMs on Intel's upcoming Nehalem chips, which use the QuickPath Interconnect, Intel's equivalent of AMD's memory design.
The R805 has two Opteron processors, while the R905 has four. The systems I reviewed have 16GB and 32GB of RAM, respectively. They have 16 and 32 DIMM slots (respectively) for 667MHz DDR 2 RAM (PC 5300), which today have a ceiling of 8GB capacity per DIMM. So, total memory currently is 128GB and 256GB, respectively -- plenty of RAM to run lots of VMs.
The servers come with up to four Gigabit Ethernet adapters. Network adapters with 10GbE capacity are expected to ship before year end. The servers also accommodate Fibre Channel HBAs, which fit into the PCIe slots. The R805 can accept four of these adapters, while the R905 will handle a maximum of seven.
A final important feature, which supports Dell's description of these systems being virtualization-optimized, is the presence of the embedded VMware ESXi installation I mentioned earlier. This feature relies on a clever design. The VMware software is installed on a memory card that is socketed in the chassis. To boot from this card, an admin enters the server's setup menu and the card is enabled as a boot device. Then at boot time, the admin lists it as the default boot drive, and Bob's your uncle.
Both server models have this option. They can also install VMware the old-fashioned way, via a DVD, as they are both endowed with optical drives.
As mentioned earlier, most virtualization hosts do not rely extensively on local disk drives for storage due to the distinct possibility that a few VMs will overwhelm the drives' I/O bandwidth. However, these servers ship with drives that can contain ESX (if you don't use the embedded version) and easily hold the VM images that you run regularly. Options are traditional 3.5-inch disks or the emerging enterprise-speed 2.5-inch disks, both of which can be configured for RAID, using the built-in controller.
Benchmarking virtualization hosts
Although virtualization has been around for decades, its surge in adoption is a comparatively recent phenomenon. As such, it does not yet benefit from industry-standard benchmarks. The first widely accepted benchmark, called GrandSlam and designed by IBM, has been retired. A second suite designed by Intel, vConsolidate, runs database, Java, mail, and Web servers and computes a performance rating by combining their results. The general industry perception is that while the vConsolidate approach is valid, its specific implementation tends to disfavor AMD processors. So, it has quietly been left aside by the industry.