In the past, I've bemoaned the fact that storage (in the form of hard disks) has gotten only about 2.5 times faster in the past 10 years, in comparison to 50 to 500 times for other parts of the typical computer. I've been looking for promising technologies that might improve storage-access speed, but nothing appears to be anywhere close to providing decent relief.
So what can you do?
Adding more cache to disk systems will speed up some operations considerably. You can also add more spindles and divide the data across a plethora of drives. A full- size EMC disk subsystem with 256 18-GB disks (for a total of 2.3 TB of usable mirrored storage) will have 16 GB of cache -- a great system if you have almost two million bucks handy. I suspect most of you do not.
What is a silicon disk?
Remember back in the bad old days, when getting around the 640-KB RAM limit in DOS was a problem? Most of us used RAM disks to speed up some operations. The operating system saw the RAM disk as a small, fast disk, though it was actually a segment of the system's memory. Of course, every time you booted the system, everything on the RAM disk went away.
While having a RAM disk sped up some operations, only static information (such as programs and lookup tables) could reliably be kept on a RAM disk.
As x86 operating systems became more robust, RAM disks faded out of the picture. A certain company based in Redmond, Wash., does still make a RAM disk driver for its newest operating systems, but hardly anybody uses it. Hard disks have grown too large for a RAM disk to be very useful.
A silicon disk is a separate box with its own power supply and battery backup. It can connect to any system that supports either SCSI or Fibre Channel disk interfaces. Some drives even have their own hard disks, for true non-volatility. If power is lost for more than a minute or two, the silicon drive backs up all its data on the hard disk. When power is restored, the data is copied back into RAM.
This week, Solid Data announced new products that give the company a line of silicon disks ranging in size from 0.5 to 17 GB.
Where can you put a silicon disk to the best use? Not by caching a 50-GB database -- at an expected street price of about $9,000 for the smallest silicon disk, caching everything is too expensive. Consider putting your most frequently accessed tables and indexes on a silicon drive.
One could argue that such indexes are already cached in the huge amounts of RAM allocated to database systems, but that's volatile RAM, reusable by the operating system. Put the data on a silicon drive and there it will stay.
Or, put frequently created temporary files, such as email queues and directory listings, on the silicon drive. Solid Data claims that this has produced an eightfold increase in some email systems' messages per hour.
Would a silicon drive benefit your operations? I can't answer that, and I bet you can't either. Only a performance test using your own data can tell you if it's worth the effort and expense.