Previously I wrote about the importance of “scalable performance” when it comes enterprise storage. My point: Enterprise-class SSDs must have sufficient back-end horsepower to scale I/O performance to meet increasing workloads for today’s data-throughput intensive applications.

Pliant recently ran a series of performance tests on several storage devices, and the results were eye opening. For baseline reference, see what happens to a typical enterprise 15K RPM hard drive as the workload increases:

Once the HDD reaches 400 IOPS, the response time starts to increase considerably to more than 75,000 microseconds (μs). And, as it reaches 500 IOPS, the response time nearly doubles, reaching more than 137,000 μs. This is the expected behavior for a mechanical device, limited by a single actuator.

Generally speaking, SSDs offer better raw I/O performance than HDDs, but when it comes to scalability and managing response time, the results are startling:

The chart above compares the STEC ZeusIOPS SAS SSD against the Pliant Lightning™ LS 300S EFD using the same saturation plot. As the workload increased, the STEC SSD’s response time increased dramatically, reaching as high as >10,000 microseconds, without significant scaling of I/O bandwidth. In contrast, the Pliant LS 300S was able keep response time below 2,000 microseconds and continued to scale I/O bandwidth to more than 32,000 IOPS.

This is the reason we designed Pliant’s Lightning Enterprise Flash Drive (EFD) to provide steady, predictable performance over time regardless of workload:

Data center I/O demands are dynamic and unpredictable by nature. As such, enterprise storage devices must have the power and flexibility to scale on-the-fly to provide a high level of performance at all times and under all workloads.

C.T. Chu

IT analyst firm Gartner recently issued its annual “Cool Vendors in Storage” report, showcasing a handful of innovative companies that are providing IT organizations with technologies to dramatically increase efficiencies and deliver measurable bottom-line benefits.

As a follow up to the report, Gartner Fellow Daryl Plummer is hosting a complimentary Webinar on May 20 – Cool Vendors 2010: Staying Cool in Economic Heat – to review the 2010 Cool Vendors, and discuss specifically how each company is poised to positively impact the IT market.

We were thrilled that Plaint was recognized among this elite group of innovators for our Enterprise Flash Drives, and I encourage you to check out the free Webinar.

The Webinar will be held twice on Thurs., May 20, and you can register online at the following links:

Register for 9 a.m. EDT/6 a.m. PDT session – https://www1.gotomeeting.com/register/933461200
Register for Noon EDT / 9 a.m. PDT session – https://www1.gotomeeting.com/register/530216081

Hope you enjoy!

Greg

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

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

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

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

Who could ask for more than seeing a new storage industry product announcement to highlight the points you’ve been trying to make?
 
I found myself in that position, and was quite surprised (well not really surprised…more like incredulous) to see a recent announcement of what had been frequently referred to as the Seagate “brick” project (not related to MiniScribe), but minimally disguised within a Seagate-funded private company.  The product that was announced is another version of a sealed unit consisting of multiple hard drives “purpose-built to maximize performance and reliability.”  The announcement makes it clear that many new techniques must have been employed to achieve “self-healing,” and to enable the product to essentially repair itself in place “to the equivalent of a fresh, factory-manufactured drive.”  Wow!  I will leave it up to people smarter than me to respond to this.

What I’d like to discuss is the price performance aspect of this announcement.  The systems tested were fully mirrored, making comparisons never quite “apples to apples.”  However, one needs to keep in mind that the MTBF of the drives employed require mirroring to reach any reasonable reliability level.  While I could not find any real price or performance data on the company’s web site, the reference to their SPC benchmarks provided considerable data.
 
From a pricing standpoint, the 1.03TB configuration sells for more than $36 per gigabyte (after a 40% discount from $60/GB)…and, flash-based SSD at $30/GB is considered expensive?
 
This benchmark is also said to be record-breaking with the lowest cost per SPC-1 IOPs.  I’m not suggesting that $36/GB is unreasonable, only that it illustrates the true cost of hard drives in high-performance environments.  A closer look at the benchmark is even more telling.  This “record-breaking” performance correlates to a response time of nearly 30 milliseconds.  In fact, response time increases dramatically starting at about 50% of the max IOPs, which is certainly troublesome for high transaction-rate systems.

This project was started a few years ago, apparently to address the growing price, performance and reliability gap in enterprise applications, as we have been talking about, and to hold off the encroachment of solid state storage devices.  However, with today’s technology, well designed Enterprise Flash Drives will not only be lower in cost per GB, less than 1/4th the cost per IOP, and more reliable.  And, did I mention power:  EFD’s will be well less than 1/100th the watts per IOPs.  I cannot help but be reminded of the Anderson Cooper segment on CNN:  “What were they thinking!”

Amyl Ahola

The dramatic reductions in HDD cost per GB have resulted in many system/storage architects (and application/operating system programmers) treating primary storage as though it is free.

Some of the results are:

• Exponential increases in the size of operating systems and applications
• Mass deployment of low-end and midrange servers with multiple copies of data (and applications)
• Over-provisioning of storage to satisfy future needs projections (which also likely adopt the concept of free storage)
• Adoption of power-hungry DRAM cache appliances to mask HDD performance shortfalls
• Over-provisioning of HDDs to mask HDD performance shortfalls

These all result in inefficient use of storage that has many costs, not the least of which is the increasing cost of energy consumption.  Some of the energy data becoming available paints a sobering picture:

• Data centers account for 1.5% of ALL U.S. electrical consumption, and this is expected to double in a few years
• Power consumption per $1,000 of server spending has increased by a factor of 4 since 2000
• Power failure and availability is expected to halt data center operations at more than 90% of all companies over the next few years
• Fifty percent of current data centers will have insufficient power and cooling capacity this year

HDDs are clearly not the only contributor to the rapid acceleration of data center power consumption, but their inefficient use is likely one of the largest contributors.  Data that suggests more than one third of data center power consumption is storage related.

Trends and techniques such as consolidation, virtualization and thin provisioning should all contribute to improved efficiencies.  But while doing so, these approaches will put increased performance demands on the HDDs.  The result:  an increased need for higher performance (i.e., higher RPM……read that as ‘power consuming’) drives and even further over-provisioning for performance – and therefore once again increased energy consumption.

It’s time for new metrics to be considered in the data centers, which take into account energy usage to aid the system designers as they optimize their systems.  Several metrics are identified at the www.greendatastorage.com website; examples cited include activity per watt, such as transactions/Watt, IOPs/Watt, and bandwidth/Watt.

I believe that Enterprise Flash Drives (EFDs) will play a major role in reversing these trends. EFDs can provide over 1000x improvement in IOPs/Watt, and an order of magnitude or more improvement in bandwidth/Watt over the highest performing HDD’s.

Amyl Ahola

Ok, I want to get back to the issue I was discussing a couple of posts ago.

The question I’m exploring is what can be done about the growing gap between disk drive and enterprise network performance, as well as the escalating inefficiencies?   One only has to look at the root cause:  the mechanical nature of disk drives.  The solution is obvious; eliminate the mechanics. 

Easier said than done! 

The Holy Grail for primary storage has always been directly addressable low latency, non-volatile random access memory.  This remains a long way off, but it is time to begin the next evolutionary step.  Solid state technology (particularly Flash) cost and performance continues to improve geometrically, and new and even more competitive semiconductor storage technologies are around the corner.  Meanwhile, disk drive performance (seek, latency) is stagnating, with only limited foreseeable improvements and with cost per I/O leveling off or even beginning to increase with time. 

Last year Greg Schulz of the StorageIO Group predicted the increasing use of solid state technology in enterprise storage applications, saying (paraphrased) that 2008 will be the year of awareness and early adoption by vendors and early deployment by customers, while 2009 will be the broader adoption phase.   Supporting that projection, EMC has recently announced their commitment to Flash and is the first major enterprise storage company to do so (http://www.emc.com/about/news/press/us/2008/011408-1.htm).  Although it was a limited announcement with what I consider an ‘entry level’ SSD technology, it is the first step towards validation of Flash technology as an enterprise primary storage device.

Solid state storage has the potential to be transformational, relegating disk drives to applications that better match their strengths, low cost per GB and large block sequential applications (for the old timers amongst us, it should be noted this is similar to the role disk played years ago with respect to magnetic tape drives).

But Flash comes with its own set of problems…(Stay tuned)

Amyl Ahola