The good people at Texas Memory Systems read and at my invitation offered this response to my post An SSD For The Rest Of Us. I think they did a pretty good job of laying out the, IMHO, historically under-appreciated RAM SSD. Naturally I have a couple of comments at the end.

*Dear Storage Mojo:*

*We are excited to see solid state disks get some coverage in your blog even if we might have different ideas about the DDR RAM solid state disk market.*

First, we like flash memory too. We like that it has high density and is non-volatile. It provides a great storage media for USB drives, cameras and even iPods. We would even want one in a notebook so that it will survive the fall a hard drive cannot, and the low power usage really adds value when you are running on batteries. The fact that all of these industries have adopted flash has led to a big drop in its price. The success of flash has cost someone some business… hard disk companies making microdrives. Interestingly, we have yet to feel any competitive pain from flash drive manufacturers.

It is worth pointing out that companies have been promoting flash memory systems for commercial business applications for years. Their prices have always been lower, their densities higher and they have always been non-volatile. Inspite of these factors, none of these companies have traction in the enterprise applications area that we sell into.

Why is that? Flash disks use flash memory and flash memory has some inherent limiting characteristics:

  1. it’s write speed is poor (comparable to disks)
  2. inspite of the best efforts of the industry it is still easy to wear out the write cycles, and finally
  3. the read speed is still a lot slower than our read speed

As an addendum to this note, we have included a description of the hard work a flash drive has to do just to get a write done.

Compare the performance specifications of the Samsung flash drive to the RamSan system:

RamSan peak IOPS: 400,000 (read or write, random or sequential)*

Samsung peak IOPS: 2,200 (Webserver IOmeter pattern) (reads only). Note that for the Database pattern it is actually lower then most single hard disks (~85 IOPS).

A flash disk in a notebook is hardly likely to wear out the write cycles from operating system boots and the occasional save of a document, but that same disk in an enterprise storage system will wear out well before the ROI is realized. If we could write 400,000 IOPS to a flash drive (which we can’t because they are way too slow) it would take us seconds to wear out the drive).

Flash systems will inevitably gain traction with the lower end of the solid state disk market but as the last few years have shown we are not really stealing market share from each other as much as we are both growing our respective markets. The flash drive companies are growing and the intensity of that market is reflected in the pace of acquisitions. Independently, Texas Memory Systems has grown its DDR RAM solid state disk market over 50% this year. The future of our combined markets has never been stronger.


Texas Memory Systems

The StorageMojo take
TMS makes a number of good points. The most powerful, IMHO, is that their RAM SSD is a big honking fast machine. Stick 8 FC ports on one and you might actually come close to those 400,000 IOPS. There really is no substitute for a big RAM SSD if that is what you need. TMS is focused on the high-end and flash is not a threat there – today.

On the other hand I detect a bit of whistling past the graveyard bravado in the TMS reply. When a product comes along on the steep downward pricing curve that flash has – much faster than disk or even RAM – that offers some of your significant advantages – non-volatility, good performance (for some apps) relative to disks – at a fraction of the cost, you have to think hard about the possibility of substitute architectures emerging.

Conjecturally, such an architecture might replace the implicit centralized schema of the TMS FC products with a distributed, shared-nothing plan. Local attach is both faster and cheaper, so if a web server farm of pizza boxes were equipped with flash SSDs, one might see a sizable fraction of TMS performance at a much lower cost without the FC management headaches. Other, less obvious, options no doubt will be invented.

Once people see a much cheaper alternative to RAM SSDs, the juices start flowing and inventions occur. If I were TMS, I’d ask a couple of my better engineers to work part time on creative flash-based SSD architectures. Somebody will, it might as well be you.