Fusion-io recently posted this blog that I wrote:   http://www.fusionio.com/blog/why-server-side-caching-rocks/

I feel strongly that 2011 will be remembered, at least in the SSD industry, for establishing the role of server-side caching using Flash.  I recall soaking in all of the activity at last year’s Flash Memory Summit and being excited about the new ways Flash was being applied to solve customer problems.  It is a great time to be in the market.  I look forward to sharing more of the market’s evolution with you.

For those of you who are interested, here is a link to a presentation that I delivered at the 2011 Flash Memory Summit on “Mission Critical Computing with SSD”.

http://www.flashmemorysummit.com/English/Collaterals/Proceedings/2011/20110810_T1B_Hutsell.pdf

I had a chance to sit down with my friends from MarketingSage (www.MarketingSage.com) at the Flash Memory Summit last week.  They asked me some tough questions about the solid state disk market, here are videos they prepared from our discussion:

Where do solid state disk cache solutions fit in the market?

How is virtualization changing demand for SSD and Flash?

What’s driving SSD sales success with end-users?

How would you describe the vendor landscape for solid state disks?

I hope you enjoy these brief videos and thanks again to MarketingSage for making it happen.

Woody

I have a point of view about third party caching (particularly as it applies to external systems as opposed to caching at the server with PCI-E) that is different than many in the industry.  Some will see this as bashing of some particular product, but it is not intended to be that.  As far as I know, I am not competing with a third party caching solution at any customer site.  My goal here is to start a discussion on third party caching, I will lead with my opinions and hope that others weigh-in.  I am open to changing my mind on this topic as I have numerous friends in the industry who stand behind this category.

First, some background.  Many years ago, 2003 to be exact, I helped bring a product to market to provide third party caching with RAM SSD.  I believed in the product and was able to get many others to believe in the product.  What I was not able to do was to get many people to buy the product.  As I look at solutions on the market, I can see that companies trying to sell third party caching solutions are encountering the same obstacles and are fixing or working around the problems.  Here are some problems I have experienced with third party caching solutions:

1.  Writes.  The really delicious problem to solve several years ago with a RAM caching appliance was related to write performance.  Many storage systems had relatively small write caching capabilities that caused major pain for write intensive applications.  A large RAM SSD (at the time I think we were using 128GB RAM) as a write cache was a major problem solver for these environments.  Several things have happened to make selling write caching as a solution more difficult:

•  RAID systems increasingly offered reasonable cache levels narrowing down the field of customers that need write caching.  At the time we offered this RAM write cache, we thought that Xiotech customers were the perfect target as they did not believe in write caching at the time. Fact is, the combined solution worked out pretty well but was only useful until Xiotech realized that offering their own write cache could solve most customer problems.

•  Third party write caching introduces a point of failure into the solution.  If you write-cache, you have to be at least as reliable as the solution you are caching otherwise you have net lost the customer reliability.

•  Write caching is nearly impossible if the backend storage array has replication or snapshot capabilities.   Arrays with snapshot have to be cache aware when they snapshot or else they risk snapshotting without the full data set.  I have seen companies try to get around this but most of the solutions look messy to me.

•  Putting a third party device from a small company in front of a big expensive product from a big company is a good way for a customer to lose support.  We realized early on that the only way for this product to really succeed was to get storage OEMs to certify it and approve it for their environments (we did not do very well at this).

2.  Reads.  Given the challenges with write caching it seems to me that most companies today are focused on read caching.  Read caching solutions have a long history.  Gear 6 was one of the first to take the space seriously and had some limited success with environments such as oil & gas HPC and rendering.  Some of the companies that have followed Gear 6, seem to be following in their footsteps with markedly different types of hardware and cost.  Here are some issues I see with read caching:

•  A third party read-only cache adds a write bottleneck (as writes to the cache have to be subsequently written to the storage). i.e. Latency injection.  I assume there are architectures that get around this today.

•  A third party read only cache really only make sense if your controller is 1) poorly cached or 2) does not have fast backend storage or 3) is processor limited or 4) has inherently poor latency.  This may be the real long term problem for this market.  Whether you talk about SAN solutions or NAS solutions all storage vendors today are offering Flash SSD as disk storage.  In SAN environments, many vendors can dynamically tier between disk levels (thus implementing their own internal kind of caching).  NetApp has Flash PAM cards. Both BlueArc and NetApp can implement read caching.  The only hope is that the customer has legacy equipment or poorly scoped their solution such that they need a third party caching product.

•  Third party caching creates a support problem.  Imagine you are NetApp and the customer calls in and says I am having problems with my NetApp storage can you fix it.  Support says, describe the environment.  Customer says “blah…blah…third party cache cache…NetApp”.  NetApp says “that is not a supported environment”.  I always saw this as a major limiting factor for third party caching solutions.  How do you get the blessing of the array/NAS vendor so that your customer maintains support after placing your box between the servers and the storage.

•  Third party read caching solutions cannot become a single point of failure for the architecture.

So, there it is. I am looking forward to some insightful comments and feedback from the industry.  As you can see many are my opinions are based on scars from prior efforts in this segment and not meant to be a reflection on existing products and approaches.

by Woody Hutsell, www.appICU.com

Instead of marketing from afar, I have been selling from the trenches and let me tell you the world looks very different from this view point.

I have a variety of observations from my first 9 months of working closely with IT end-users:

1. At least 50% of the IT people I talk to are generally unfamiliar with solid state storage.  These 50% are so busy worrying about backups, replication, storage capacity and virtualization that it would take a whole screaming train full of end users before they would care about performance.  What they are likely to think they know about SSD is that they are unreliable and don’t have great write performance.  I always ask these end users about performance or interest in SSD and usually get fairly blank looks back.  Don’t get me wrong, their interest in performance or SSD is no reflection on them just a reflection on their situation.  Maybe they don’t need any more performance than they already get from their storage.  Maybe performance is so far down their list of concerns as to not matter.  Maybe they just can’t budget a big investment in SSD.
2. Some high percentage of IT buying is done without any real research.  So much for technical marketing.  You could write any number of case studies, brochures and white papers and these guys wouldn’t learn about it unless the sales person sitting across from them drops in at just the right time immediately after the aforementioned train full of end-users has started complaining about performance (and the IT guy happens to have budget to spend on something other than backup, storage capacity, replication or virtualization).
3. These groups are deploying server virtualizationin mass.
4. These groups are standardizing on low cost storage solutions.  The rush to standardize is driven by the number one reality affecting many IT shops:  they are under staffed and their budgets are constrained.  The lack of staffing means that it is hard to get staff trained on multiple products and life is easier if they can manage multiple components from a single interface.  The lack of budget means that IT buyers have to make compromises when it comes to storage solutions.  Because of item #2 (above), they are reasonably likely to buy storage from their server vendor and often find their way to the bottom of the storage line-up to save money.

You might think these observations would be disheartening, but really I think the story is that SSD is just starting to make its way through to the more mature buyers in the market.  Eventually, I believe that all IT storage buyers will be as familiar with and concerned with protecting application performance as they are with capacity and reliability.

A case in point, I have run into at least two customers where the drive to standardize with VMWare and low cost storage is crushing application performance for mission critical applications.  The good news for these IT shops is they have low storage costs and an easy to manage environment (because they have one storage vendor and one server virtualization solution).  The bad news is that their core business is suffering.

From my limited point of view, standardization is something that the IT guys like and the application owners don’t like.  You might assume that I think the IT guys are short-sighted, but no, increasingly I am seeing that they just don’t have a choice; they have to standardize or die under a staggering workload and shrinking budget.  Something though has to give.  A core business of one of these operations was risk analysis.  This company deployed low-cost storage and had virtualized the entire IT environment with VMWare (including the SQLServer database).  The entire IT infrastructure ran great for this customer but a mission critical sub-terabyte database was a victim of standardization.  The risk managers, whose decisions drove business profitability, were punished every time they did complex analyses by slow application response time.  The second business is really a conglomerate of some 50+ departments.  These departments were not created equally, however, there were some really profitable big departments and some paper-pushing small departments.  To the benefit of some end users and the tremendous detriment of others this business standardized on a middle tier storage solution with generous capacity scalability but not so generous performance scalability.  Their premier revenue generating department was suffering with, you won’t believe this, 60 millisecond latencies from storage for their transaction processing system.  Yikes.  For the non-storage geeks reading this blog, a really fast solid state storage system will return data to the host in well under 1 millisecond.  A well-tuned hard disk based RAID array will return data in 5 to 7 milliseconds.  A 60 millisecond response time is indicative of a major storage bottleneck.  Experiencing a 60 millisecond response time on a single request is no big deal but when this is during a batch process or spread across many concurrent users applications get to be very slow, end-users wait for seconds or batch process take too long to complete resulting in blown batch processing windows.

For now, the story for these two environments is not finished.  Once companies head down the standardization trail they are pretty confident and committed.  Eventually, the wheels fall off and people begin to realize that it is as bad to standardize on all low cost storage as it is to standardize on all high end storage.  Eventually, people realize that IT needs to align to business and not the other way around.

As companies amass larger data stores and the price and options for deploying SSD evolves, SSD solutions will become more common in the data center and a part of each IT manager’s bag of tricks.  Zsolt Kerekes, at StorageSearch.com, put it best in his 2010 article “This Way to Petabyte SSD” (http://www.storagesearch.com/ssd-petabyte.html) when he said “The ability to leverage the data harvest will create new added value opportunities in the biggest data use markets – which means that backup will no longer be seen as an overhead cost. Instead archived data will be seen as a potential money making resource or profit center. Following the Google experience – that analyzing more data makes the product derived from that data even better. So more data is good rather than bad. (Even if it’s expensive.)”

The next big opportunity/threat for SSD manufacturers is playing itself out right now. SSD vendors are scrambling to be a part of this next big wave. The winners are your next acquisition targets or companies poised to go public. The losers will hope that this new wave expands the overall market just like the first wave.

The first big wave in the enterprise SSD market was the rapid adoption of hard disk form factor SSDs for use in enterprise storage arrays. The SSD companies most seriously contending to ride this wave were BitMicro and STEC. STEC, by virtue of their GnuTek acquisition, had the right product at the right time and were able to win early business with EMC. Suddenly, venture money was pouring into the market and any company that had ever put a Flash chip on a board was selling Flash disk drives. The clear winners in this category have been STEC, who continues to have great revenue growth, and Pliant’s investors who have successfully sold their company to SanDisk after getting some traction with the OEM community. The story in this market is not finished as companies like Western Digital, Seagate, LSI and Intel look to chip away at this part of the business. At the same time though, a few companies were swept out to sea and others saw their golden opportunity for enterprise riches turn into dreams of big volumes (but low margins) in consumer markets. As I have argued before, the use of Flash hard drives in enterprise arrays is really about accelerating infrastructures more than about accelerating a specific application. This first big wave actually increased opportunities for all SSD companies by increasing the market size and validating the technology for mainstream use.

The newest wave to entice and yet concern SSD manufacturers is hitting closer to home for those manufacturers focused on the application acceleration market. For many years, the data warehousing sector has led to some great success stories for companies like Netezza who tightly bundled database functionality with hardware. Netezza’s success led Oracle and HP to try Exadata which was anything but a rousing success in the market. But somewhere along the way, Oracle was watching what Sun was doing with solid state storage and noticed a way to take the relatively less exciting Exadata and turn it into something much more captivating and yet similarly named Exadata 2. Some day we will learn whether the prospects of Exadata 2 were a big motivator for the Sun acquisition or just a quick way to demonstrate that Oracle was serious about the hardware market. Either way, Oracle’s claims of big margins and big potential revenue streams for Exadata 2 have ignited a flurry of activity in the market. Already vendors are clamoring to get into this space and there is a series of speed dating exercises going on as database vendors, server vendors and SSD vendors start trying to find some magical combination which helps them beat Oracle at this new market. Will the rich SSD vendors get richer still in this category or will the remaining SSD manufacturers find new partners, buyers and OEMs? Can any combination beat Oracle?

Whoever the winners, this second wave will show more clearly the ability of a tightly integrated solid state storage solution to increase application performance.

In late 2006, Robin Harris at www.StorageMojo.com wrote “RAM-based SSDs are Toast –Yippie ki-yay”.  As a leader of the largest RAM-based solid state storage vendor at the time, I can assure you that his message was not lost on me.  In fact, we posted a response to Robin in “A Big SSD Vendor Begs to Differ” to which Robin famously responded “If I were TMS, I’d ask a couple of my better engineers to work part time on creative flash-based SSD architectures.”  I cannot honestly remember the timing, but it is fair to say that the comment minimally reinforced our internal project to develop a system that relied heavily on SLC NAND Flash for most of its storage capacity.  Within a few years, TMS had transitioned from a RAM-based SSD company to a company whose growth was driven primarily by Flash-based SSD.  Nearly five years after the predicted death of RAM-based SSD I thought it would be interesting to evaluate the role of RAM SSD in the application acceleration market.

First off, it is important to note that RAM-based SSDs are not toast.  In fact, a number of companies continue to promote RAM-based SSDs including my employer, ViON, who is still marketing, selling and supporting RAM-based SSDs.  What may be more surprising is that the intervening years have actually seen a few new companies join the RAM-based SSD market.  What all of these companies have identified is that there are still use cases for the high-performance per density available with RAM-based SSD.  In particular, RAM-based SSDs continue to be ideal for database transaction logs, temporary segments or small to medium databases where the ability to scale transactions without sacrificing latency is critical.  Customers in the e-commerce, financial and telecom markets will still use RAM SSD.  When a customer says to me that they need to do be able to say they have done “everything possible” to make a database fast, I still point them to RAM SSD if the economics are reasonable.  I think the RAM SSD business has promise for these specific use cases and will watch with curiosity the companies that try to expand the use cases to much higher capacities.

The second thing to note is that without RAM, Flash SSDs would not be all that appealing.  You will probably all recall the reaction to initial Flash SSDs that had write performance slower than hard disk drives.  How did the vendors solve this problem?  Well for one thing they over-provisioned Flash so that writes don’t wait so much on erases.  In enterprise solutions, however, the real solution is RAM.  Because the NAND Flash media just needs a little bit of help, a small amount of RAM caching goes a long way toward decreasing write latencies and dramatically improving peak and sustainable write IOPS.  This increases the cost and complexity of the Flash SSD but makes it infinitely more attractive to the application acceleration market.

Third, the companies with the most compelling Flash SSD performance characteristics have come out of the RAM SSD market.  These companies had developed low latency, high bandwidth controllers and backplanes that were tuned for RAM.  Contrast this with the difficulties the integrated storage manufacturers have had since their controllers and backplanes were tuned for hard disk drives.

Casual industry observers might ask a couple of other questions about this market:

• With the rapid decrease in RAM prices, is RAM likely to replace Flash as the storage media of choice for enterprise SSD?  No.
• Are the large integrated storage companies likely to add a non-volatile RAM SSD tier in front of their new Flash SSD tier?  I tend to doubt it, but would not rule it out completely.
• Aren’t customers that start with Flash going to look to RAM SSD to go even faster?  I think some of these customers will want more speed but for most users Flash will be “good-enough”.
• Aren’t customers that start with RAM likely to move to Flash SSD on technology refreshes?  Probably not.  RAM SSD is addictive.  Once you start with RAM SSD, it is hard to contemplate going slower.

To put this all in perspective, Flash SSDs did not kill the RAM SSD market.  In some ways, Flash SSD and the big companies who have embraced it have added legitimacy to the RAM SSD market that it lacked for decades.  I think RAM SSDs will continue to be an important niche in the overall application acceleration market and anticipate innovative companies introducing new use cases and products over the next five years.

To give credit where credit is due while Flash SSDs did not kill the RAM SSD market, it has come to dominate the enterprise storage landscape like no other technology since the advent of disk storage.  Robin Harris may not have accurately predicted the end of RAM SSD but he was at the forefront of analysts and bloggers, including Zsolt at www.StorageSearch.com, predicting Flash SSD’s widespread success.

As a participant in the SSD industry for the last decade, I have had the benefit of watching the ascent of Fusion-IO from a small start-up company to a marketing machine and can now observe along with the rest of you their attempt to go public.

Say what you will about Fusion-IO and their products, and believe me at various times I have said all of those things good and bad, they are a marketing machine. But to leave it at that would be a terrible injustice. David Flynn and his team launched a product that the rest of us did not see the need for. Don’t get me wrong, Cenatek and MicroMemory both had server-based PCI SSDs well before Fusion-IO, but Fusion-IO did two things that really set their product apart 1) they were the first PCI SSD company to really take advantage of the first generation of Flash suitable for enterprise customers; 2) they were unashamed about beating their way into the enterprise market even if they took what I consider a fire:ready:aim approach to marketing. I remember the early days of Fusion-IO marketing which was clearly aimed at companies using storage area networks. The ad went something like “the power of a SAN in your server”. Interesting concept, but the people who used storage area networks were pretty sure that a PCI card was not about to replace their SAN. I know, some people have done this but by and large I would suggest that what Fusion discovered and now markets to directly is the large set of customers that need server-based application acceleration. These scale-out applications include those run at customers like Facebook who improve application performance by adding servers. Historically, those servers would be laden with expensive high-density RAM. Fusion-IO brought them a product that was not cheap, but less expensive than RAM. The other sweet spot that Fusion discovered was that this market was very read-intensive and good therefore to use MLC Flash enabling the customers to get better density and better pricing.

I remember the first time I met David Flynn. I was participating in a SNIA Summer Symposium in early 2008. Until this point, my only real exposure to Fusion-IO had been from their marketing. When the topic in the room turned to Flash technology, David was quick to join the discussion and showed a grasp of Flash that clearly exceeded that of most of the people in the room. From that point, I knew that Fusion was much more than marketing.

At one point during my time at TMS I tried to assess what it was that made Fusion-IO go from yet another random company involved in SSD to a company that was always in the limelight (disproportionately to their revenues – another hallmark of good marketing). I used Google trends data to see if there was an inflection point for Fusion-IO and I found it. The inflection point was their hiring of Steve Wozniak. What a brilliant publicity move and one that I think continues to pay off for Fusion-IO. From the day his involvement with Fusion-IO was announced, the company took off in terms of web hits. I can’t tell you how much time, because it would be embarrassing, but I spent a lot of time trying to figure out how to create a similar event at TMS. I thought if we could hire “Elvis” we would have a chance.

The next brilliant tactical move by Fusion-IO was tying up the server OEMs. You see, one of the biggest challenges with selling products that go into another manufacturer’s servers is getting that server vendor to bless and support the solution. Fusion realized this problem early on and announced relationships with HP, IBM and Dell. Not to mention that Michael Dell was an investor. The big problem was solved with the announcements, the big server vendors had blessed Fusion-IO with credibility typically reserved for companies like Seagate and Intel. It is worth noting that these server vendors hate single sourced products leaving plenty of room for competitors to get the same blessings.

Plenty of things good and bad have happened along the way for Fusion-IO. They encountered many of the problems that fast-growing venture backed companies have. There were delayed product releases, there were quality problems, Fusion’s approach to business created a lot of enemies, they went through an impressive number of CEOs (though David Flynn remained the key guy all along) and sales teams, and there were missteps in channel marketing strategy but through it all they have shown impressive perseverance.

As Fusion’s revenues have grown in the last two years to match their marketing, they have added some really impressive depth to their team. Marius Tudor who largely led the sales & marketing efforts for industry pioneer BitMicro is involved. Another marketing genius, Gary Orenstein who led marketing at Gear 6 among other places has joined the team. This is not to imply that I don’t have deep respect for their Chief Marketing Officer Rick White, another gaming enthusiast like myself, but really, does he need this much help. Leaving behind some marketing talent for the rest of the industry would have been gracious.

For the SSD vendor community, whatever you think of Fusion-IO, their effort to go public is a major milestone for the industry. Have you ever tried to get private company valuations without comparables? Valuations become guesswork. Do you have a great SSD idea and need VCs to get excited about it? Fusion-IO successfully going public would help the rest of the private companies eying their own exit strategy (going public, staying private, being acquired). What does it take for an SSD company to go public? What revenue, what profitability, what gross-margins? We may soon find out. In this pursuit, I for one am rooting for Fusion-IO and in turn the industry.

One of the key concepts in data center replication is the concept of consistency groups.  A consistency group is a set of files that must be backed up/replicated/restored together with the primary data in order for the application to be properly restored.  Consistency groups are the cause of the most difficult discussions between end-users and SSD manufacturers.  At the end of this article, I will suggest some solutions to this problem.

The largest storage manufacturers have a corner on the enterprise data center marketplace because they have array-based replication tools that have been proven, in many locations over many years.  For replicated data to be restored, an entire consistency group must be replicated using the same tool set.  This is where external SSDs encounter a problem.  External SSDs are not typically (though this is changing) used to store all application data; furthermore, they do not usually offer replication.  In a typical environment, the most frequently accessed components of an application are stored on SSD and the remaining, less frequently accessed data, are stored on slower, less expensive disk.  If a site has array-based replication, that array no longer has the entire consistency group to replicate.

External SSD write caching solutions encounter a more significant version of this same problem.  Instead of storing specific files that are accessible to the array-based replication tool, it has cached some writes that may, or may not be, flushed through to the replicating array.  The replicating array has no way of knowing this and will snapshot or replicate and not have a full set of consistent data because some of that data is cached in the external caching solution.  I am aware that some of these third party write caching solutions do have a mechanism to flush cache and allow the external array to snapshot or replicate, but generally speaking, these caching SSDs have historically been used to cache only reads, since write-caching creates too many headaches.  Unless the external caching solution is explicitly certified and blessed by the manufacturer of the storage being cached, using these products for anything more than read caching can be a pretty risky decision.

Automatic integration with array-based replication tools is a main reason that some customers will select disk form factor SSD rather than third party SSDs, in spite of huge performance benefits from the third party SSD.  If you are committed to attaining the absolute highest performance, and are willing to invest just a little bit of effort to maximize performance, the following discussion details some options for getting around this problem.

Solution 1:  Implement a preferred-read mirror.  For sites committed to array-based replication, a preferred-read mirror is often the best way to get benefit from an external SSD and yet keep using array-based replication.  A preferred-read mirror writes to both the external SSD and to the replicating SAN array.  In this way, the replicating array has all of the data needed to maintain the consistency group and yet all reads come from the faster external SSD.  One side benefit of this model is that it allows a site to avoid mirroring two expensive external SSDs for reliability, saving money.  This is because the existing array provides this role.  If your host operating system or individual software application does not offer preferred read mirroring, then a common solution is to use third-party storage application such as Symnatec’s Veritas Storage Foundation to provide this feature.  You must bear in mind that a preferred read mirror does not accelerate writes.

Solution 2:  Implement server-based replication.  There are an increasing number of good server-based replication solutions.  These tools allow you to maintain consistency groups from the server rather than from the controller inside the storage array, allowing one tool to replicate multiple heterogeneous storage solutions.

Solution 3:  For enterprise database environments, it is common for a site to replicate using transaction log shipping.  Transaction log shipping makes sure all writes to a database are replicated to a remote site where a database can be rebuilt if needed.  This approach takes database replication away from the array – moving things closer to the database application. 

Solution 4:  Implement a virtualizing controller with replication capabilities.  A few external SSD manufacturers have partnered with vendors that offer controller based replication and who support heterogeneous external storage behind that controller.  This moves the SSD behind a controller capable of performing replication.  The performance characteristics of the virtualizing controller now are a gating factor in determining the effectiveness, and indeed the value added by the external SSD.  In other words, if the virtualizing controller adds latency (it must) or has bandwidth limitations (generally they do), those will now apply to the external SSD.  This can slow SSDs down by a factor of from three to ten times.  It is also the case that this approach will solve the consistency group problem only if the entire consistency group is stored behind the virtualizing controller.

Most companies implementing external SSD have had to make decisions, trying to grapple with the impact of consistency groups on application performance, replication and recovery speed.  Even so, the great speed associated with external SSDs often leads them to implement external SSD using one of the solutions we have discussed. 

What has been your experience?

Fibre Channel SSDs are aimed at the enterprise data center. For most of the last decade, Fibre Channel has been the interface of choice for Tier 1 disk drives and the main interface for attaching external storage arrays in most data centers. Interestingly, the Tier 1 disk drives are now migrating to SAS, but the predominant interface for the enterprise storage array to the server is still Fibre Channel. Companies developing Fibre Channel SSDs want to appeal to enterprise data centers who have made major investments in Fibre Channel based storage area networks. There are plenty of predictions about the demise of Fibre Channel in the data center, but if you were making a choice about an interface for the enterprise today, you would offer Fibre Channel first. If I were deciding the next interface for an SSD or a storage array, I might go with FCOE, but I would probably wait to see that market develop further first. The rapid introduction of converged network adapters (CNA) could translate into changes at the storage controller, but I would also wait to see what happens in that arena.

InfiniBand SSDs are aimed at the high performance computing (HPC) market. InfiniBand is touted for its high bandwidth per link and its low latency. For SSDs with large backplanes, an InfiniBand (IB) controller is a good way to tout your bandwidth capability. Yes, I know there are other companies using IB outside of the HPC market, but the bulk of big opportunities for IB SSD are in that space today. I broadly define HPC to also include oil & gas and entertainment industries. I do believe that IB attached SSDs are an interesting option for data warehousing applications where bandwidth is more important than IOPS.

 NAS SSDs are aimed at the middle of the enterprise. This segment is one of the more intriguing to watch. A couple of companies have made credible attempts to develop NAS caching solutions which sit in front of existing NAS and provide a read or read/write caching layer. In a future blog, I might examine the challenges these companies face. As with mainstream Fibre Channel attached storage, the NAS vendors have incorporated SSD as a storage tier. Only one vendor comes to mind that is doing a pure SSD NAS solution, but others are likely to follow. NAS solutions are so much about software that it is harder for a new company to enter this space and compete with the incumbent suppliers.

iSCSI SSDs are aimed at the low to middle of the enterprise. This has not been a terribly active segment for pure SSD solutions but interesting options are on the horizon. Clearly, existing iSCSI storage arrays have options for including hard disk based SSDs. My automatic expectation when I look at an iSCSI solution is that it will be less expensive than a Fibre Channel SSD. The main reason I would offer iSCSI is to target the cost-sensitive part of the market. Given the increased availability of 10Gbit Ethernet and advanced TCP off-load engines, it is quite reasonable for an iSCSI SSD to offer good performance.

Internal PCI SSD. There has to be an exception to every rule and PCI SSD may be the exception to my rule about an interface telling you about the application for an SSD. PCI SSDs cover a wide variety of price ranges, capacities, media, performance and reliability. On the high end, there are a bunch of applications, particularly scale-out applications, which are server-centric and not storage network centric. PCI SSD have had tremendous success in this category. Similarly, for companies with smaller data sets and budgets, PCI SSD can be alluring. It is not a stretch to pitch PCI SSD for prosumer or high end gaming customers.

External SAS SSD. There are very few externally attached SAS SSDs on the market today. I think the people who offer them were probably temporarily delusional about the future role of SAS in the market and its ability to get rid of Fibre Channel for storage networking. This is not to say that SAS is a bad interconnect, in fact it is being effectively used to replace Fibre Channel as the backplane for many modern storage arrays (i.e. the connections between a disk controller and its enclosures are increasingly SAS).

Hard Disk Drive (HDD) Form Factor SAS SSD.  With the help of solid state storage, SAS HDD has killed the Fibre Channel disk drive. Hard drive form factor SSDs with SAS interfaces are more likely than not intended to be sold to a storage or server OEMs. For the storage OEMs, they replace their Fibre Channel SSDs (if they were ever offered). For the server OEMs, SAS SSD may be used as a boot drive.

SATA SSDs are aimed at the consumer, prosumer, gaming and small business markets. I cannot currently see an enterprise market for SATA SSD. In enterprise storage arrays, SATA HDDs are only used to offer the 3.5” high density (slower) drives.

External PCI. There are a few varieties of external PCI offerings including devices that are ground up designed to offer external PCI SSD and others that are I/O expansion chassis that can be loaded up with PCI SSD. My personal opinion is that the genesis of the external PCI SSD was to serve as extended memory for servers at a time when server memory capacities were limited and at high densities extremely expensive. In my experience, the only way to make one of these devices useful for traditional data centers is to put the external PCI chassis behind some other storage gateway. The storage gateway attaches to the storage network with Fibre Channel. This is all good, but the gateway is now the main dictator of your performance characteristics.

The story on SSD interfaces is certainly not complete. Innovative companies will capitalize on new markets and new interfaces in ways that we cannot yet predict. For the innovators in these segments lie new markets and new opportunities.