When we asked the IT pros in the Server Room to name the number one barrier to solid state disk (SSD) adoption in the enterprise, "price" was the near unanimous consensus. SSD storage is still significantly more expensive than rotating magnetic media, but with datacenters becoming ever more constrained by power and cooling considerations, the overall price picture for SSD vs. HDD keeps getting better. Sure, at the level of an individual drive, the cost/GB difference between SSD and HDD is still huge, but at the level of the overall datacenter, with floor space, power, and cooling factored in, the delta now looks a lot smaller.

The latest large datacenter to make the leap to SSD is MySpace, a division of Fox Interactive that has recently been shrinking a lot more than just its server footprint—user base, revenues, and staff come to mind. The struggling social networking site has a mandate to boost efficiency, so it turned to FusionIO, makers of PCIe-based SSDs with insanely high sustained read and write bandwidth numbers to match their stratospheric prices (80GB will set you back around $3,500—and it only gets worse from there).

Despite the sticker shock, MySpace took the jump, and both companies detailed the results in a white paper. For starters, the ioDrive 320GB let the company cut the size of its individual servers in half, moving from 2U HPDL380 to 1U HP DL160 servers and cutting the total amount of deployed hardware by 60 percent and saving 280U of rack space. Of course, each of those ioDrive 320GB units retails for close to $7,000, and each server used two, so it cost MySpace quite a bit to cut out all of that hardware. The company plans to replace the rest of its server fleet with SSD hardware as it reaches end-of-life.

Not every datacenter will be able to replicate MySpace's costly feat of hardware compression, though. As a social networking platform, MySpace is essentially a giant database application with a huge number of concurrent connections. The MySpace engineers claim that the ioDrive-hosted parts of the database ran as fast as if they had been cached in a RAM drive. As one of the participants in the aforementioned SSD discussion remarked, even at current prices, SSD already makes plenty of sense for datacenters that are performance-constrained instead of capacity-constrained, and MySpace appears to fall into the performance-constrained camp.

The power savings for the SSD-based systems is about 50 percent, and the overall cooling savings are 80 percent, according to the white paper. These savings are significant for a datacenter that spends 40 percent of its budget on power and cooling, and they're bound to make other datacenter operators sit up and take notice. The paper suggests that these savings will more than pay for the ioDrives over the course of their lifetime.

The one problem that SSD migration won't help with is the amount of floor space that's already wasted in power-constrained datacenters. Many datacenters have huge tracts of unused floor space, because their power systems reach capacity long before they run out of racks. In reducing the amount of hardware in MySpace's datacenter by 50 percent, SSD has just made this problem that much worse. In this respect, the datacenter of the medium-term future may look like a ghost town, with large tracts of empty racks and disconnected cabling punctuated by a few actual systems.