A criticism I often hear from industry insiders and ‘experts’ is that the higher cost and TCO (Total Cost of Ownership) of SSD technology is a significant barrier to rapid and widespread enterprise adoption.

Nothing could be further from the truth.

I believe that this stems from the fact that the industry is stuck on using the HDD metric of $/GB and single drive cost as the primary measures of the cost. As I wrote in a previous post, “Storage managers getting wise to prevailing SSD limitations”, looking at historical or single drive cost metrics doesn’t accurately measure solution-level costs. So let’s try this again.

Yes, individual enterprise-class solid state drives (Enterprise Flash Drives) cost more than individual enterprise hard drives. So having stated this fact, let’s also be sure to state the fact that EFDs offer tremendous performance boosts (>100X), and can replace many 15K RPM HDDs. Budget constraints require that enterprises and data centers focus on maximizing both performance and efficiency, so transaction cost ($/IOPS) is also a key metric.

The goal is to provide a storage solution that optimizes for both $/GB and $/IOPS.

Let’s look at a typical data warehousing application from the TPC-C benchmarks (http://www.tpc.org/tpcc/results/tpcc_perf_results.asp). The storage solution must provide 640,000 transactions/minute (320,000 IOPS) for 18 TB of data. With a typical all-HDD solution, this requires:

• 1000 15K 2.5-inch HDDs (short stroked to 18GB)
• 40 rack mounted shelves
• 8000 watts to operate and (an additional) 8000 watts to cool
• Price tag = $ 450,000

Now, let’s look at how a ‘hybrid’ approach combining EFDs and existing HDDs can not only provide a lower transaction cost, but also a lower cost/GB and a lower total cost. This hybrid solution would be configured as outlined below:

Not only does the hybrid approach offer a much lower $/GB and $/IOP (and requires 34 fewer shelves), but the total cost is one-half that of the HDD-only configuration.

Did you catch that?  One-half the total cost.

At the end of the day, the numbers don’t lie. The value proposition of EFDs is simple, it provides ‘more for less’ – more performance for less cost, less power and floor space, and more reliability. And, EFDs can be managed with existing software.

What will IT managers do with all the savings?

Amyl Ahola

The industry is catching on to what I’ve been talking about for some time: flash technology offers tremendous value for the enterprise, yet adoption hinges on addressing the prevailing limitations of existing SSDs first.

This ‘revelation’ appeared in a SearchStorage.com article by Beth Pariseau, “Storage admins mull SSDs at SNW.”  The article quotes multiple storage administrators who all basically believe in the benefits of SSD, but stop short of saying that the technology is ready for prime time.

Here are their top concerns: predictable performance, data integrity, the lack of consistent, industry-accepted SSD benchmarks, and cost.

Let’s quickly look at each of these:

1. Predictable performance – I covered this recently in my “’Predictable performance’ for changing business dynamics” post. This area has traditionally been a challenge for SSDs in enterprise applications because workloads are random and indeterminate. Predictability requires consistent performance, independent of whether reading or writing data, because enterprise applications typically vary the read-to-write ratio between 60/40 and 90/10. Enterprise SSDs should be able to maintain performance across this range.
2. Data integrity – I couldn’t agree more that data integrity features are critical if flash technology is to perform at enterprise levels, and the Data Integrity Field (DIF) standard is an important step in this direction. Yet, today so few storage devices support the DIF standard. Pliant began mapping toward the DIF standard early on, recognizing how important it was for enterprise-class storage systems.
3. Standardized benchmarks – In my post, “SSD jargon and the need for standards,” I listed a number of pivotal questions that must be addressed if the industry is ever to develop more accurate, relevant – and yes, consistent – SSD benchmarks. These include making sure that real performance is measured and that product lifecycle benchmarks are based on true, 100% duty cycle operation. If product life metrics are contingent on usage limitations – e.g., based on a maximum number of writes or writes per day due to limited error management capability – then the benchmarks are virtually useless.
4. Cost – Transaction cost (IOPS per $) is the key SSD metric to consider, not the old HDD industry metric of $/GB. This metric is an irrelevant measure of SSD value as a performance solution, and we expect EFDs (Enterprise Flash Drives) to complement high capacity HDDs to optimize for both $/IOP and $/GB.

With most existing vendors either falling short on a number of these points, or masking the limitations of their devices behind carefully crafted marketing spin, it’s no wonder why some storage admins are still skeptical.

This is why I continue to extol the values of EFDs, a new class of solid state storage devices designed with key enterprise considerations in mind. By definition, EFDs are designed to address all of the above issues.

And, as we prepare to announce availability of our first products shortly, my hope is that our approach will help turn the heads and change the minds of the remaining nay-sayers in the industry.

Amyl Ahola

Now, here’s someone who really understands the benefits and value of using Enterprise Flash Drives (EFDs) in enterprise IT data centers:  Mark Peters.

Mark covers data center storage and systems for Enterprise Strategy Group.  He was recently interviewed for a SearchStorage.com “FAQ Guide” podcast about the growth in enterprise solid state technology.  (Read the full transcript here)

In the interview, Mark addresses the questions he hears most often from storage administrators about solid state technology, and I have to say that his views are spot-on — particularly regarding the benefits and value of solid state, and the market/business drivers that are making the technology increasingly attractive.

A few of the key points Mark makes are:

1)  I/O performance benefits

“Generically, whatever is most important to a business or enterprise or organization in terms of getting throughput and I/O handled, wherever you need speed, wherever you need a great deal of performance in terms of throughput, then solid state will be great.”

2)  Energy efficiency

“Given that we’re in such challenging economic times, that makes solid state more interesting.  Obviously with my focus on the data center I look at the green aspect of computing as well, and it’s hard to overlook solid state from that perspective.”

3)  Cost-efficiency

“Even in terms of today’s pricing, cost per I/O or the I/O per watt for solid state are already very compelling.”

It’s nice to see Mark (and other industry experts) start to recognize the important and growing role EFDs will play in the future.

Amyl Ahola

PS.  Mark also has a blog with more great info on a variety data center storage issues:  Mark My Words.  I suggest checking it out if you haven’t already.

You don’t need a crystal ball to predict how the global economic slowdown and a prolonged recession will impact IT spending in 2009:  it’s going to be ugly.  Many projects will be delayed, eliminated outright, or at the very least, cut severely in scope. 

This poses a huge problem for enterprise IT managers. Why? 

Quite simply, enterprise information demands continue to increase with no end in sight.  And, data center managers will have to do anything and everything in their power — without making significant new IT capital investments —to keep up with the increasing IT system performance demands. 

Failure to do so will be unacceptable, so what are the options?

Two things come to mind:  1) optimizing existing IT systems for increased performance; and 2) significantly reducing the energy consumption of power-hungry high RPM hard disk racks.  Is this difficult? 

It may be easier than one thinks and requires no change to the existing infrastructure, management software or systems.  By adding Enterprise Flash Drives (EFDs) to handle the performance workload of many spinning hard drives, both goals can be achieved.  The high performance of the EFD enables more I/Operformance and flexibility to meet peak periods and growing demands.  By combining EFDs with high capacity HDDs, today’s storage racks can be reduced to storage shelves saving power (up to 80%), space and money. 

I predict that beginning in 2009, EFDs will be a key tool for enterprise IT managers to survive the economic turmoil while optimizing their existing storage systems.

And, let’s face it, it’s time for a change to the traditional approach to high-performance storage solutions. 

Interested to hear your feedback, so please feel free to comment.

Amyl Ahola

In a previous blog, I suggested that performance, reliability, IOPS per watt, and IOPS per $ are key storage metrics for enterprises. However, satisfying demanding enterprise needs goes far beyond the attainment of just these metrics. I/O-intensive enterprise IT applications require IOPS and bandwidth levels to be predictable and sustainable across a variety of workload requirements.

Predictable performance has traditionally been a challenge for SSDs in enterprise applications because workloads are random and indeterminate. This means that predictability requires consistent performance, independent of whether reading or writing data, as enterprise applications typically vary the read-to-write ratio between 60/40 and 90/10.  Ensuring that predictable performance is maintained while the workload changes is another example of how an Enterprise Flash Drive (EFD) offers differentiation from traditional SSDs. 

A performance comparison (IOmeter-based) between a well-publicized ‘enterprise’ SSD and the new Pliant EFD illustrates this difference.  From the chart, you can see how the ‘enterprise’ SSD(I) performance drops by over 80% as the read/write ratio changes. The Pliant EFD maintains its performance across the range from 100% reads to a 50/50 read/write ratio. This is because the Pliant EFD can read and write simultaneously to the drive and therefore offer substantially better and predictable performance for these demanding applications. Traditional SSDs and HDDs can only perform one read or write at a time. 

The bottom line: EFDs enable enterprises to achieve higher I/O performance, maintain performance predictability with changing workloads, offer higher levels of service quality, and dynamically address changing business requirements without adding additional hardware.   

I’m curious to hear what you think, so please feel free to comment.

Amyl

It’s clear to many industry experts that the enterprise storage landscape is changing dramatically.  And, as I’ve said, soon just about every enterprise data center in the world will be using enterprise flash drives (EFDs) for at least a portion of their data storage needs due to the accelerated requirements for higher levels of I/O performance, as well as the growing pressure to cut energy costs.

I was recently published in Systems Management News, so check out the article for greater detail.Click to link here:  http://www.sysmannews.com/link/32853. 

I’m curious to hear what you think, so feel free to comment.

Amyl Ahola

If you’ve been following my blog you’re undoubtedly aware of my views on the advantages of Enterprise Flash Drives (EFDs) over “traditional” SSD technology.

However, as with any new technology, it takes some time for the concept to catch on and for the industry to understand how the technology works and how it can solve real IT and business problems.  So, under the heading of “Industry Education,” I’m very excited that there is an EFD Wikipedia (www.wikipedia.org) definition that clearly outlines EFD benefits, characteristics and applications. 

Take a look:  http://en.wikipedia.org/wiki/Enterprise_Flash_Drive

The great thing about having a universal EFD definition is that it will allow any IT or storage professional to easily access a real-time, detailed explanation of the technology.  Also, because Wikipedia is in the public domain, the EFD definition will evolve as the market grows and the technology advances – making it always relevant to the challenges and issues IT managers will face now and in the future.

Amyl Ahola

I have written about a new class of SSDs referred to as Enterprise Flash Drives (EFDs) many times.  But what does it take to make a true “enterprise-class” SSD drive?  With so many different SSDs targeted for the enterprise it can be difficult to tell which SSDs really qualify as EFDs, and which do not. 

So, I think a description and definition is in order. 

In the world of disk drives, enterprise-class products are distinguished from desktop and laptop products by their ability to provide superior performance and reliability.  This means that they are expected to perform flawlessly in mission critical environments.  This same requirement also holds true for enterprise SSD devices.  However, just like lower-end disk drives, SSDs designed for laptops and desktops simply can’t pass muster when expected to provide the performance and reliability required in a mission-critical enterprise environment.  There are a number of existing SSD products marketed for the enterprise, many of which are nothing more than re-packaged consumer grade (laptop) SSD technology.  In fact, many of the so-called “enterprise SSD” drives actually underperform HDDs in laptop applications…hardly what I would call enterprise class. 

Therefore, a true EFD must provide high levels of performance and reliability for flawless operation in mission critical, I/O-intensive environments.  Given the growing power and space concerns of today’s large enterprise environments, reduced energy consumption is becoming an equally important criterion for any new class of primary storage devices.  An EFD’s superior performance, energy efficiency and improved reliability allow data centers to substantially grow capacity and performance in existing installations while reducing energy needs and TCO.

Given these requirements, an Enterprise Flash Drive should, at a minimum, provide the following:

1. Superior I/O Performance – Adequate I/O performance levels to prevent bottlenecks, even during peak activity periods (generally 3-5 times greater than typical activity periods), without requiring extra hardware (i.e., cache)  while providing ample scalability for growth.  At a minimum, an EFD should deliver at least 100,000 random IOPS or more and be able to sustain this rate for typical block sizes (4K bytes or more). 
2. Exceptional Reliability – EFDs need to deliver significantly lower failure rates than disk drives, given the inherent benefit of solid state technology (no moving parts).  Performance and reliability must be predictable and sustainable at 100 percent duty cycles (24/7/365) without cycle-stealing maintenance or “housekeeping” actions.  Lifetime should exceed five years without performance or capacity degradation.  Robust reliability monitoring and reporting capabilities are essential.
3. Energy Efficiency – EFDs should meet new standards for green data center excellence of greater than 20,000 IOPS per Watt, with activity-based power management to limit energy consumption when the device is less than 100 percent utilized.
4. Cost Efficiency – Transaction costs ($/IOPS) must be substantially reduced from that of an HDD (<10%).  And, it goes without saying that an EFD must be form factor and interface compatible with HDDs (while providing similar storage capacities).

While these requirements are very demanding, I believe they only begin to define the needs and ability of solid state technology to transform future system and storage architectures.  In my opinion, the vast majority of today’s SSD products are already falling short of the true needs. 

Interested to hear what you think…

Amyl Ahola

I just read a very interesting on Computerworld.com article written by Jim Damoulakis http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9092918

Jim suggests that we’re on the verge of a “SSD Revolution” because of the significant performance advantage of Flash over disk drives. He makes several compelling and informative points regarding the pros and cons of SSD technology; however, I really wish he didn’t begin the article by discussing SSD in laptops. I believe the enterprise storage industry is missing an important distinction by making comparisons to consumer SSD products when discussing the adaptation of the technology in the enterprise. There are fundamental differences between commodity consumer-grade and enterprise-class products. Comparing consumer and enterprise flash based products is a little like comparing myself to Tiger Woods; we both play golf but, believe me, the similarities end there.

I’ve written a lot about I/O performance on this blog, and with good reason.  When I discuss Pliant’s EFD device and enterprise IT system performance issues with partners and the press, one of the questions that almost always comes up is about performance.  But, I often point out that, just like when considering a sports car, performance is only part of the equation.  Reliability is of equal importance as well.

Enterprise storage applications are demanding, and it is essential that reliability specifications are met at a 100-percent duty cycle operation on a 24/7/365 basis.  Those in the industry know that true enterprise-class disk drives are required for this environment, and that disk drives designed for low cost and low duty cycle laptop/desktop applications literally fall apart when employed in an enterprise application.  Likewise, SSDs designed for laptop/desktop applications also do not even come close to meeting the need.  So, for Enterprise Flash Drives to be accepted in the enterprise they must meet or exceed enterprise class HDD reliability. This is not a trivial task. 

The primary enterprise reliability specifications take the form of MTBF (or more meaningfully: annualized failure rate) and non-recoverable error rates (lost data).  Flash technology has three primary failure phenomenon that have a significant impact on reliability:

• Write Endurance – the limit on how many times a cell can be written/erased before it becomes damaged
• Write/Program Disturb –  writing to a given page in a Flash chip can alter bit(s) in a page that is not being written (does not damage the cell); this is sometimes referred to as “bit flip”
• Read Disturb – similar to Write Disturb, reading a page in a Flash chip can alter bit(s) in a page not being read (does not damage the cell)

A further complication is that these failure modes are not independent.  For example, the read disturb error rate is related to the number of writes or erases so that write endurance and read disturbs (and write disturbs) must be holistically considered.  It is obvious that they all contribute to non-recoverable errors, but perhaps not as obvious that they contribute to MTBF as well.  MTBF is a measurement of performance to specification, not just to some catastrophic event, as is typical with a disk drive.  This includes meeting performance and capacity specifications.

A common approach used in typical SSDs to deal with write endurance is to incorporate a wear-leveling algorithm to distribute writes across blocks within the chip(s), together with error correction (ECC), so that any damaged cells can be corrected when read.  This same ECC can then be applied for all reads to detect and correct altered bits (‘bit flips’) independently of how they became defective, i.e., write endurance, read disturb, or write disturb.  If the number of defective bits exceeds the ECC threshold, the sector(s) being read would then have to be marked as defective (non-recoverable error) and made unavailable to the system.  Depending on the amount of spare Flash capacity, at some point the resulting system capacity may well drop below the specification.

As an example, a well-known supplier of SSDs advertises an ECC that corrects up to 8 bytes in 1024 bytes, while another supplier advertises 6 bytes in 528 bytes.  At the same time, both talk about program erase/write cycles well in excess of 1 million.  However, tests show that both ECC levels would frequently result in non-recoverable errors after as few as 200,000 write/erase cycles.  These error rates result in SSD reliability falling far short of disk drive reliability in terms of non-recoverable error rate.  At the same time, overall capacity begins to erode and eventually falls below the device specification, resulting in an MTBF failure. 

And, that’s not all.  There is also a significant performance impact resulting from the management of these high error rates (It drops dramatically!).

The primary point is that enterprise-level reliability, whether it’s MTBF or non-recoverable error rate, can not be addressed with just traditional ECC.  Other techniques must be employed in addition to ECC to manage errors.  In addition, these additional techniques cannot be allowed to significantly impact performance (IOPs or bandwidth).

Sounds like a daunting task…or is it??  Stay tuned.

 Amyl Ahola