Flash

HDD & SSD Combined Into One

Wafer Scale HDDThe SSD Guy has often explained to readers that the storage industry is caught between two alternatives:  fast and costly, or cheap and slow.  This is the key difference between SSDs and HDDs.  I have recently learned of a new secret government research effort, code named “SiliDisk,” that will provide the best of both worlds by marrying flash memory with the mechanics of an HDD.

The approach is incredibly ingenious, while remaining deceptively simple: All that is required is to replace the disks in an HDD with the wafers used to manufacture NAND flash.  Both are round, so there’s little engineering effort to switch from a magnetic disk to a flash wafer.

The NAND flash on the wafer is almost completely standard.  The only two changes are that the chips aren’t scribed or sawn apart, saving a small sum, but a hole must be etched through the center (which can be seen in the photo below) offsetting this savings.  The HDD mechanisms are unchanged with one exception: While today’s HDDs are largely manufactured using 2.5″ and 3.5″ platters (65mm & 90mm), NAND flash is exclusively produced on 300mm wafers.  This means that Continue reading

Flash vs. DRAM in PCs – Flash Wins

Chart from Objective Analysis report: How PC NAND will Undermine DRAMSome time ago Objective Analysis ran nearly 300 standard benchmarks on a PC with varying amounts of flash and DRAM and found that a dollar’s worth of flash provided a greater performance boost than a dollar’s worth of DRAM once the DRAM size grew above a certain minimum (1-2GB) depending on the benchmark.

You might wonder how this could possibly be true.  Everyone knows that best way to improve any computing system’s performance is to add DRAM main memory.  How could flash, which is orders of magnitude slower than DRAM, provide a bigger performance boost than DRAM?

It all makes sense if you think of the DRAM of something that is there only to make the HDD look faster.  More is better, but if you can use a little less DRAM and add a large flash memory layer then disk accesses appear to speed up even more.

The benchmark data and the price/performance findings that are Continue reading

MLC vs. eMLC – What’s the Difference?

eMLCFrom time to time IT managers ask The SSD Guy if there’s an easy way to compare SSDs made with MLC flash against those made using eMLC flash.  Most folks understand that eMLC flash is a less costly alternative to SLC flash, both of which provide longer wear than standard MLC flash, but not everyone realizes that eMLC’s superior endurance comes at the cost of slower write speed.  By writing to the flash more gently the technology can be made to last considerably longer.

So how do you compare the two?  OCZ introduced MLC and eMLC versions of the same SSD this week, and this provides a beautiful opportunity to explore the difference.

As you would expect, the read parameters are all identical.  This stands to reason, since Continue reading

IBM Makes Flash Even Faster

IBM Edge ConferenceAt IBM’s Edge 2013 conference last week the company not only extolled the values of flash, as does anyone who has had a flash experience, but it also showed how flash could be made even faster than it already is.

You’re probably already thinking: “Flash is about 1,000 times as fast as HDD – how do you make it even faster?”

The answer is actually pretty simple: compress the data.  If there is a limit to how much bandwidth you have going into and out of a piece of storage, you can speed it up if you can reduce the size of the data that consumes that bandwidth.

Of course, that’s not always easy.  Compression often slows data access down, even for HDDs, and it could Continue reading

IBM to Invest $1B in Flash Promotion

The following is excerpted from an Objective Analysis Brief e-mailed to our clients on 15 April, 2013:

Comparison of 3-Year Operating Costs: Flash vs HDD (Wikibon)On April 11 IBM kicked off “The IBM Flash Ahead Initiative”, committing to spend more than $1 billion for flash systems and software R&D and to open twelve IBM Flash Centers of Competency around the world staffed with flash experts armed with flash systems to help clients test drive flash in their own situations.

This follows from IBM’s August 2012 agreement to acquire privately-held Texas Memory Systems (TMS), a very low profile manufacturer of high-performance flash-based memory arrays and PCIe SSDs. TMS is the world’s oldest SSD maker, founded in 1976, to manufacture RAM-based replicas of HDDs. About four years ago TMS used its Continue reading