Christian Bolton (http://twitter.com/christianbolton) re-tweeted a message last week about the capabilities of HP’s new DL165G7 server which can deliver 12 CPU cores and 256GB of memory in 1U chassis (http://bit.ly/dtpBGA). With quad core CPUs replacing dual core it wasn’t a surprise to see AMD’s 6 core Opteron CPU hit the marketplace alongside Intel’s 6-core options however, what surprised me was the jump in memory which even the smallest of server chassis is now supporting.
For a while I’ve just known that server hardware could support more memory than I ever needed and not known exactly how much they could provide. But now consolidation with virtualisation and increasing database sizes has given us an appetite for as much memory as we can have and with memory prices decreasing almost linearly year on year the server manufacturers have responded.
The latest range of mid-enterprise HP DL380 servers now come with 6 or 8 more DIMM slots than the previous generation, along with 12 CPU cores. For those with deep pockets HP’s DL500 range supports 24 cores per 4U chassis but still only 256GB memory. I suspect lack of free physical space is preventing this from getting any larger just yet, at least until 16 and 32GB DIMMS become more common.
Having this amount of CPU and memory (and one assumes connected SAN storage) is great but can I actually find a use for it? Well increasingly now the answer is yes. The editions of the software products I commonly see deployed have supported through their licensing agreements this scale of hardware for a while; there just hadn’t been the suitable hardware available at an affordable price-point.
Due to the way Microsoft’s SPLA licensing works almost all of the managed/hosted database servers I see use SQL Server Standard Edition on Windows Server Enterprise Edition. Even for those consuming more traditional licence types Microsoft’s “per-CPU” licensing model has always counted CPU sockets not cores so as core counts have increased from 1, to 2, to 4 and now to 6 we have in effect received free SQL Server performance upgrades courtesy of Microsoft.
Crucially though, what we’re now able to do thanks to having so many DIMM slots is fill the server with 24(!) smaller but cheaper DIMMs. 24 2GB DIMMs still gives 48GB of memory but at a much lower cost than 12 months ago with only 12 slots. SQL Server Standard Edition will support as much memory as the operating system allows, 2TB for Enterprise Edition on X64, and for most OLTP systems that’s a huge amount of cache waiting to replace physical I/O reads.