Following our news piece yesterday about new servers supporting fully buffered DIMMs, it would be prudent of us to mention Crucial's FBDIMM modules, released this month.
A problem with memory, that exists not just for servers, but for workstations and desktops too, is that there are (unsurprisingly) drawback to the two progressions we all seek. Making memory faster can lead to more errors, as interconnects are pushed to their limits. Making memory denser can lead to the need to reduce their speed. Neither situation is ideal, so naturally DRAM, DIMM, motherboard and chip manufacturers are always looking at ways to improve the situation.
The latest (and greatest?) solution, currently making its way into servers, is the FBDIMM. To quote Crucial's white paper on FBDIMMs:
FBDIMMs feature an advanced memory buffer (AMB) that buffers the DRAM data pins from the channel and uses high-speed point-to-point lines (serial signaling similar to PCI Express) to eliminate the stub bus.
Basically, the serial nature of the connection means more DIMMs can be hung off a memory controller and they can be run faster. The end result is more memory capacity and upgradeability, along with better throughput. Along with that, FBDIMMS feature a number of error checking and handling techniques that reduce the likelihood of errors, without killing performance; great news for servers.
Crucial's FBDIMMs range from 512MiB to 4GiB in density, at speeds of 533MHz or 667MHz. Find a table of them over at Crucial.com.
FBDIMM sounds great on paper, so it'll be interesting to see how well it works in Intel servers, compared to AMD-based rigs, for which FBDIMM seems to be a way off yet.
