In-memory computing is all the rage. But there are problems with large memory servers: DIMMs use a lot of power and board space, and DIMMs are expensive.

When it comes to low latency and high bandwidth, the memory bus is hard to beat. But a terabyte? Diablo Technologies has announced one.

The secret is using flash instead of DRAM. Flash is much denser, lower cost, and uses much less power. And it's cheaper, too.

As a result, you can put 1 terabyte of flash on a standard-size DIMM. This moves in-memory computing from expensive technology for critical apps to a much more affordable technology for many applications.

How did they do it?

The TeraDIMM looks to the system just like a regular DIMM. The form factor and power are the same. There are no changes to the motherboard or applications, only a driver — available for Windows, Linux, and VMware — that makes the device look like either storage or system memory.

Of course, flash memory lacks some very important characteristics of DRAM. It wears out; it takes much longer to write; and it needs specialized controllers to manage all of its issues.

This is the secret sauce of the new product. An ASIC manages the flash and makes it look like either storage or extended main memory.

Endurance: The product is designed to handle 10 full capacity writes — 10TB for a 1TB DIMM — every day for five years.

Performance: 3-5µs write latencies.

Capacity: Multiple modules can be pooled by the driver. Driver can broadcast rates to multiple modules for availability.

Use cases:

Virtual machines: There is lots of read-only traffic in VMware. Placing virtual machines in main memory is significantly faster.

High-frequency messaging: Low constant latency, even better than PCIe devices.

Memcache: Uses main memory as a much bigger cache. Popular in hyper-scale clusters.

The Storage Bits take

There have been non-volatile DIMMs on the market before this. But this is the first one I've seen that that has all the elements needed for success: unique technology; economic advantage; top-tier VC and OEM support; and use cases in a rapidly growing part of the market.

No, you probably will not be buying these for your gaming rig. This is intended as an enterprise server class technology, and it will be priced as such.

But this brings new life to the concept of in-memory computing. Imagine 8TB of main memory to begin to see the possibilities.

Comments welcome, as always. How would you use a terabyte — or more — of main memory?