Learn the Latest on Persistence at the 2020 Persistent Memory Summit

The 2020 SNIA Persistent Memory Summit is coming to the Hyatt Regency Santa Clara on Thursday, January 23, 2020. The day before, on January 22, an expanded version of the SNIA Persistent Memory Hackathon will return, co-located again with the SNIA Annual Members Symposium. We’ll share Hackathon details in an upcoming SNIA Solid State blog. For those who have already attended a Persistent Memory Summit, you will find significant changes in the makeup of the agenda.  For those who have never attended, the new agenda might also be an opportunity to learn more about development options and experiences for persistent memory. The focus of the 2020 Summit will be on tool and application development for systems with persistent memory.  Read More

Register for the PIRL Conference Today

Registration is now open for the upcoming Persistent Programming in Real Life (PIRL) Conference – July 22-23, 2019 on the campus of the University of California San Diego (UCSD). The 2019 PIRL event features a collaboration between UCSD Computer Science and Engineering, the Non-Volatile Systems Laboratory, and the SNIA to bring industry leaders in programming and developing persistent memory applications together for a two-day discussion on their experiences. Read More

Register for the PIRL Conference Today

Registration is now open for the upcoming Persistent Programming in Real Life (PIRL) Conference – July 22-23, 2019 on the campus of the University of California San Diego (UCSD).

The 2019 PIRL event features a collaboration between UCSD Computer Science and Engineering, the Non-Volatile Systems Laboratory, and the SNIA to bring industry leaders in programming and developing persistent memory applications together for a two-day discussion on their experiences.

PIRL is a small conference, with attendance limited to under 100 people, including speakers.  It will discuss what real developers have done, and want to do, with persistent memory. Most of the presentations will include demonstrations of live code showing new concepts.  The conference is designed to be a meet-up for developers seeking to gain and share knowledge in the growing area of Persistent Memory development.

PIRL features a program of 18 presentations and 5 keynotes from industry-leading developers who have built real systems using persistent memory.  They will share what they have done (and want to do) with persistent memory, what worked, what didn’t, what was hard, what was easy, what was surprising, and what they learned.

This year’s keynote presentations will be:

  • * Pratap Subrahmanyam (Vmware): Programming Persistent Memory In A Virtualized Environment Using Golang
  • * Zuoyu Tao (Oracle): Exadata With Persistent Memory – An Epic Journey
  • * Dan Williams (Intel Corporation): The 3rd Rail Of Linux Filesystems: A Survival Story
  • * Stephen Bates (Eideticom): Successfully Deploying Persistent Memory and Acceleration Via Compute Express Link
  • * Scott Miller (Dreamworks): Persistent Memory In Feature Animation Production

Other speakers include engineers from NetApp, Lawrence Livermore National Laboratory, Oracle, Sandia National Labs, Intel, SAP, Red Hat, and universities from around the world.  Full details are available at the PIRL website.

PIRL will be held on the University of California San Diego campus at Scripps Forum, a state-of-the-art conference facility just a few meters from the beach.  Discounted early registration ends July 10, so register today to ensure your seat.

How Many IOPS? Users Share Their 2017 Storage Performance Needs

New on the Solid State Storage website is a whitepaper from analysts Tom Coughlin of Coughlin Associates and Jim Handy of Objective Analysis which details what IT manager requirements are for storage performance. The paper examines how requirements have changed over a four-year period for a range of applications, including databases, online transaction processing, cloud and storage services, and scientific and engineering computing.  Read More

Attend Live – or Live Stream – SNIA’s Persistent Memory Summit January 18

by Marty Foltyn

SNIA’s Persistent Memory Summit makes its fifth annual appearance in Silicon Valley next Wednesday, January 18, and if you are in the vicinity of the Westin San Jose, you owe it to yourself to check it out. PMSummitLogo (2)

SNIA is well known for its technology-focused, no vendor-hype conferences, and this one-day event will feature 12 presentations and two panels that will “level set” the discussion, review persistent memory usage, describe applications incorporating PM available today, discuss the infrastructure and implementation, and provide a vision of the “next generation” of persistent memory.

You’ll meet speakers from SNIA member companies Intel, Micron, Microsemi, VMware, Red Hat, Microsoft, AgigA Tech, Western Digital, and Spin Transfer.  Live demonstrations of persistent memory solutions will be featured from Summit underwriters Intel and the SNIA Solid State Storage Initiative, and Summit sponsors Microsemi, VMware, AgigA Tech, SMART Modular, and Spin Transfer.

Registration is complimentary but limited  -visit http://www.snia.org/pm-summit for the complete agenda and how to sign up.  And, if your travels don’t permit you to attend in person, the Persistent Memory Summit will be live-streamed on the SNIAvideo channel at https://www.youtube.com/user/SNIAVideo.

Your Questions Answered on NVDIMM

The recent NVDIMM webcasts on the SNIA BrightTALK Channel sparked many questions from the almost 1,000 viewers who have watched it live or downloaded the on-demand cast. Now,  NVDIMM SIG Chairs Arthurnvdimm blog Sainio and Jeff Chang answer 35 of them in this blog.  Did you miss the live broadcasts? No worries, you can view NVDIMM and other webcasts on the SNIA webcast channel https://www.brighttalk.com/channel/663/snia-webcasts.

FUTURES QUESTIONS

What timeframe do you see server hardware, OS, and applications readily adopting/supporting/recognizing NVDIMMs?

DDR4 server and storage platforms are ready now. There are many off-the shelf server and/or storage motherboards that support NVDIMM-N.

Linux version 4.2 and beyond has native support for NVDIMMs. All the necessary drivers are supported in the OS.

NVDIMM adoption is in progress now.

Technical Preview 5 of Windows Server 2016 has NVDIMM-N support
 

How, if at all, does the positioning of NVDIMM-F change after the eventual introduction of new NVM technologies?

If 3DXP is successful it will likely to have a big impact on NVDIMM-F. 3DXP could be seen as an advanced version of a NVDIMM-F product. It sits directly on the DDR4 bus and is byte addressable.

NVDIMM-F products have the challenge of making them BYTE ADDRESSBLE, depending on what kind of persistent media is used.

If NAND flash is used, it would take a lot of techniques and resources to make such a product BYTE ADDRESSABLE.

On the other hand, if the new NVM technologies bring out persistent media that are BYTE ADDRESSABLE then the NVDIMM-F could easily use them for their backend.
How does NVDIMM-N compare to Intel’s 3DXPoint technology?

At this point there is limited technical information available on 3DXP devices.

When the specifications become available the NVDIMM SIG can create a comparison table.

NVDIMM-N products are available now. 3DXP-based products are planned for 2017, 2018. Theoretically 3DXP devices could be used on NVDIMM-N type modules

 

 

 

PERFORMANCE AND ENDURANCE QUESTIONS

What are the NVDIMM performance and endurance requirements?

NVDIMM-N is no different from a RDIMM under normal operating conditions. The endurance of the Flash or NVM technology used on the NVDIMM-N is not a critical factor since it is only used for backup.

NVDIMM-F would depend on various factors: (1) is the backend going to be NAND Flash or some other entity? (2) What kind of access pattern is going to be done by the application? The performance must be at least same as that of NVDIMM-N.

Are there endurance requirements for NVDIMM-F? Won’t the flash wear out quickly when used as memory?

Yes, the aspect of Flash being used as a RANDOM access device with MEMORY access characteristics would definitely have an impact on the endurance.
NVDIMM-F – Doesn’t the performance limitations of the NAND vs. DRAM effect the application?

NAND Flash would never hit the performance requirements of the DRAM when seen as an entity to entity comparison. But, in the whole perspective of a wider solution, the data path of DRAM data -> Persistence Data in a traditional model would have more delays contributed by a good number of software layers involved in making the data persistent versus, in the NVDIMM-F the data that is instantly persistent — for just a short term additional latency.
Is there extra heat being generated….does it need any other cooling (NVDIMM-F, NVDIMM-N)

No
In general, our testing of NVDIMM-F vs PCIe based SSDs has not shown the expected value of NVDIMMs.  The PCIe based NVMe storage still outperforms the NVDIMMs.

TBD
What is the amount of overhead that NVDIMMs are adding on CPUs?

None at normal operation
What can you say about the time required typically to charge the supercaps?  Is the application aware of that status before charge is complete?

Approximately two minutes depending on the density of the NVDIMM and the vendor.

The NVDIMM will not be ready because the charging status and in turn the system BIOS will wait; until it times out if the NVDIMM is not functioning.

USE QUESTIONS

What will happen if a system crashes then comes back before the NVDIMM finishes backup? How the OS know what to continue as the state in the register/L1/L2/L3 cache is already lost?

When system comes back up, it will check if there is valid data backed up in the NVDIMM. If yes, backed up data will be restored first before the BIOS sets up the system.

The OS can’t depend on the contents of the L1/L2/L3 cache. Applications must do I/O fencing, use commit points, etc. to guarantee data consistency.

Power supply should be able to hold power for at least 1ms after the warning of AC power loss.

Is there garbage collection on NVDIMMs?

This depends on individual vendors. NVDIMM-N may have overprovisioning and wear levering management for the NAND Flash.

Garbage collection really only makes sense for NVDIMM-F.
How is byte addressing enabled for NAND storage?

By default, the NAND storage can be addressed only through the BLOCK mode addressing. If BYTE addressability is desired, then the DDR memory at the front must provide sophisticated CACHING TECHNIQUES to trick the Host Memory Controller in to thinking that it is actually accessing a larger capacity DDR memory.
Is the restore command issued over the I2C bus?  Is that also known as the SMBus?

Yes, Yes
Could NVDIMM-F products be used as both storage and memory within the same server?

NVDIMM-F is by definition only block storage. NVDIMM-P is both (block) storage and memory.

 

COMPATIBILITY QUESTIONS

 

Is NVDIMM-N support built into the OS or do the NVDIMM vendors need to provide drivers? What OS’s (Windows version, Linux kernel version) have support?

In Linux, right from 4.2 version of the Kernel, the generic NVDIMM-N support is available.

All the necessary drivers are provided in the OS itself.

Regarding the Linux distributions, only Fedora and Ubuntu have upgraded themselves to the 4.x kernel.

The crucial aspect is, the BIOS/MRC support needed for the vendor specific NVDIMM-N to get exposed to the Host OS.

MS Windows has OS support – need to download.
What OS support is available for NVDIMM-F? I’m assuming some sort of drivers is required.

Diablo has said they worked the BIOS vendors to enable their Memory1 product. We need to check with them.

For other NVDIMM-F vendors they would likely require drivers.

As of now no native OS support is available.
Will NVDIMMs work with typical Intel servers that are 2-3 years old?   What are the hardware requirements?

The depends on the CPU. For Haswell, Grantley, Broadwell, and Purley the NVDIMM-N are and/or will be supported

The hardware requires that the CPLD, SAVE, and ADR signals are present

Is RDMA compatible with NVDIMM-F or NVDIMM-N?

The RDMA (Remote Direct Memory Access) is not available by default for NVDIMM-N and NVDIMM-F.

A software layer/extension needs to be written to accommodate that. Works are in progress by the PMEM committee (www.pmem.io) to make the RDMA feature available transparently for the applications in the future.

SNIA Reference: http://www.snia.org/sites/default/files/SDC15_presentations/persistant_mem/ChetDouglas_RDMA_with_PM.pdf
What’s the highest capacity that an NVDIMM-N can support?

Currently 8GB and 16GB but this depends on individual vendor’s roadmaps.

 

COST QUESTIONS

What is the NVDIMM cost going to look like compared to other flash type storage options?

This relates directly to what types and quantizes of Flash, DRAM, controllers and other components are used for each type.

 

MISCELLANEOUS QUESTIONS

How many vendors offer NVDIMM products?

AgigA Tech, Diablo, Hynix, Micron, Netlist, PNY, SMART, and Viking Technology are among the vendors offering NVDIMM products today.

 

Is encryption on the NVDIMM handled by the controller on the NVDIMM or the OS?

Encryption on the NVDIMM is under discussion at JEDEC. There has been no standard encryption method adopted yet.

If the OS encrypts data in memory the contents of the NVDIMM backup would be encrypted eliminating the need for the NVDIMM to perform encryption. Although because of the performance penalty of OS encryption, NVDIMM encryption is being considered by NVDIMM vendors.
Are memory operations what is known as DAX?

DAX means Direct Access and is the optimization used in the modern file systems – particularly EXT4 – to eliminate the Kernel Cache for holding the write data. With no intermediate cache buffers, the write operations go directly to the media. This makes the writes persistent as soon as they are committed.

Can you give some practical examples of where you would use NVDIMM-N, -F, and –P?

NVDIMM-N: load/store byte access for journaling, tiering, caching, write buffering and metadata storage

NVDIMM-F: block access for in-memory database (moving NAND to the memory channel eliminates traditional HDD/SSD SAS/PCIe link transfer, driver, and software overhead)

NVDIMM-P: can be used either NVDIMM-N or –F applications
Are reads and writes all the same latency for NVDIMM-F?

The answer depends on what kind of persistent layer is used.   If it is the NAND flash, then the random writes would have higher latencies when compared to the reads. If the 3D XPoint kind of persistent layer is used, it might not be that big of a difference.

 

I have interest in the NVDIMMs being used as a replacement for SSD and concerns about clearing cache (including credentials) stored as data moves from NVM to PM on an end user device

The NVDIMM-N uses serialization and fencing with Intel instructions to guarantee data is in the NVDIMM before a power failure and ADR.

 

I am interested in how many banks of NVDIMMs can be added to create a very large SSD replacement in a server storage environment.

NVDIMMs are added to a system in memory module slots. The current maximum density is 16GB or 32GB. Server motherboards may have 16 or 24 slots. If 8 of these slots have 16GB NVDIMMs that should be like a 96GB SSD.
What are the environmental requirements for NVDIMMs (power, cooling, etc.)?

There are some components on NVDIMMs that have a lower operating temperature than RDIMMs like flash and FPGA devices. Refer to each vendor’s data sheet for more information. Backup Energy Sources based on ultracapacitors require health monitoring and a controlled thermal environment to ensure an extended product life.
How about data-at-rest protection management? Is the data in NVDIMM protected/encrypted? Complying with TCG and FIPS seems very challenging. What are the plans to align with these?

As of today, encryption has not been standardized by JEDEC. It is currently up to each NVDIMM vendor whether or not to provide encryption..

 

Could you explain the relationship between the NVDIMM and the IO stack?

In the PMEM mode, the Kernel presents the NVDIMM as a reserved memory, directly accessible by the Host Memory Controller.

In the Block Mode, the Kernel driver presents the NVDIMM as a block device to the IO Block Layer.
With NVDIMMs the data can be in memory or storage. How is the data fragmentation managed?

The NVDIMM-N is managed as regular memory. The same memory allocation fragmentation issues and handling apply. The NVDIMM-F behaves like an SSD. Fragmentation issues on an NVDIMM-F are handled like an SSD with garbage collection algorithms.

 

Is there a plan to support PI type data protection for NVDIMM data? If not, achieving E2E data protection cannot be attained.

As of today, encryption has not been standardized by JEDEC. It is currently up to each NVDIMM vendor whether or not to provide encryption.

 

Since NVDIMM is still slower than DRAM so we still need DRAM in the system? We cannot get rid of DRAM yet?

With NVDIMM-N DRAM is still being used. NVDIMM-N operates at the speed of standard RDIMM

With NVDIMM-F modules, DRAM memory modules are still needed in the system.

With NVDIMM-P modules, DRAM memory modules are still needed in the system.
Can you use NVMe over ethernet?

NVMe over Fabrics is under discussion within SNIA http://www.snia.org/sites/default/files/SDC15_presentations/networking/WaelNoureddine_Implementing_%20NVMe_revision.pdf

 

SNIA’s Persistent Memory Education To Be Featured at Open Server Summit 2016

sssi boothIf you are in Silicon Valley or the Bay Area this week, SNIA welcomes you to join them and the Solid State Storage Initiative April 13-14 at the Santa Clara Convention Center for Open Server Summit 2016, the industry’s premier event that focuses on the design of next- generation servers with topics on data center efficiency, SSDs, core OS, cloud server design, the future of open server and open storage, and other efforts toward combining industry-standard hardware with open-source software.

The SNIA NVDIMM Special Interest Group is featured at OSS 2016, and will host a panel Thursday April 14 on NVDIMM technology, moderated by Bill Gervasi of JEDEC and featuring SIG members Diablo Technology, Netlist, and SMART Modular. The panel will highlight the latest activities in the three “flavors” of NVDIMM , and offer a perspective on the future of persistent memory in systems. Also, SNIA board member Rob Peglar of Micron Technology will deliver a keynote on April 14, discussing how new persistent memory directions create new approaches for system architects and enable entirely new applications involving enormous data sets and real-time analysis.

SSSI will also be in booth 403 featuring demonstrations by the NVDIMM SIG, discussions on SSD data recovery and erase, and updates on solid state storage performance testing.  SNIA members and colleagues can register for $100 off using the code SNIA at http://www.openserversummit.com.

Are Hard Drives or Flash Winning in Actual Density of Storage?

The debate between hard drives and solid state drives goes on in 2016, particularly in the area of areal densities – the actual density of storage on a device.  Fortunately for us, Tom Coughlin, SNIA Solid State Storage Initiative Education Chair, and a respected analyst who contributes to Forbes, has advised that flash memory areal densities have exceeded those of hard drives since last year!

Coughlin Associates provides several charts in the article which map lab demos and product HDD areal density since 2000, and contrasts that to new flash product announcements.  Coughlin comments that “Flash memory areal density exceeding HDD areal density is important since it means that flash memory products with higher capacity can be built using the same surface area.”

Check out the entire article here.

SNIA NVM Summit Delivers the Persistent Memory Knowledge You Need

by Marty Foltyn

The discussion, use, and application of Non-volatile Memory (NVM) has come a long way from the first SNIA NVM Summit in 2013.  The significant improvements in persistent memory, with enormous capacity, memory-like speed and non-volatility, will make the long-awaited promise of the convergence storage and memory a reality. In this 4th annual NVM Summit, we will see how Storage and Memory have now converged, and learn that we are now faced with developing the needed ecosystem.  Register and join colleagues on Wednesday, January 20, 2016 in San Jose, CA to learn more, or follow http://www.snia.org/nvmsummit to review presentations post- event.

The Summit day begins with Rick Coulson, Senior Fellow, Intel, discussing the most recent developments in persistent memory with a presentation on All the Ways 3D XPoint Impacts Systems Architecture.

Ethan Miller, Professor of Computer Science at UC Santa Cruz, will discuss Rethinking Benchmarks for Non-Volatile Memory Storage Systems. He will describe the challenges for benchmarks posed by the transition to NVM, and propose potential solutions to these challenges.

Ken Gibson, NVM SW Architecture, Intel will present Memory is the New Storage: How Next Generation NVM DIMMs will Enable New Solutions That Use Memory as the High-Performance Storage Tier . This talk reviews some of the decades-old assumptions that change for suppliers of storage and data services as solutions move to memory as the new storage

Jim Handy, General Director, Objective Analysis, and Tom Coughlin, President, Coughlin Associates will discuss Future Memories and Today’s Opportunities, exploring the role of NVM in today’s and future applications. They will give some market analysis and projections for the various NVM technologies in use today.

Matt Bryson, SVP-Research, ABR, will lead a panel on NVM Futures-Emerging Embedded Memory Technologies, exploring the current status and future opportunities for NVM technologies and in particular both embedded and standalone MRAM technologies and associated applications.

Edward Sharp, Chief, Strategy and Technology, PMC-Sierra, will present Changes Coming to Architecture with NVM. Although the IT industry has made tremendous progress innovating up and down the computing stack to enable, and take advantage of, non-volatile memory, is it sufficient, and where are the weakest links to fully unlock the potential of NVM.

Don Jeanette, VP and John Chen, VP of Trendfocus will review the Solid State Storage Market, discuss what is happening in various segments, and why, as it relates to PCIe.

Dejan Vucinc, HGST San Jose Research Center will discuss Latency in Context: Finding Room for NVMs in the Existing Software Ecosystem. HGST Research has been working diligently to find out where is there room in the existing hardware/software ecosystem for emerging NVM technology when viewed as block storage rather than main memory. Vucinc will show an update on previously published results using prototype PCI Express-attached PCM SSDs and our custom device protocol, DC Express, as well as measurements of its latency and performance through a proper device driver using several different kinds of Linux kernel block layer architecture.

Arthur Sainio, Director Marketing, SMART Modular and Co-Chair, SNIA NVDIMM SIG, will lead a panel on NVDIMM. discussing how new media types are joining NAND Flash, and enhanced controllers and networking are being developed to unlock the latency and throughput advantages of NVDIMM.

Neal Christiansen, Principal Development Lead, Microsoft, Microsoft will discuss Storage Class Memory Support in the Windows OS. Storage Class Memories (SCM) have been the topic of R&D for the last few years and with the promise of near term product delivery, the question is how will Windows be enabled for such SCM products and how can applications take advantage of these capabilities.

Jeff Moyer, Principal Software Engineer, Red Hat will give an overview of the current state of Persistent Memory Support in the Linux Kernel.

Cristian Diaconu, Principal Software Engineer, Microsoft will present Microsoft SQL Hekaton – Towards Large Scale Use of PM for In-memory Databases, using the example of Hekaton (Sql Server in-memory database engine) to break down the opportunity areas for non-volatile memory in the database space.

Tom Talpey, Architect File Server Team, Microsoft, will discuss Microsoft Going Remote at Low Latency: A Future Networked NVM Ecosystem. As new ultra-low latency storage such as Persistent Memory and NVM is deployed, it becomes necessary to provide remote access – for replication, availability and resiliency to errors.

Kevin Deierling, VP Marketing, Mellanox will discuss the role of the network in developing Persistent Memory over Fabrics, and what are the key goals and key fabric features requirements.

SNIA’s Solid State Storage Initiative Advances the Industry at Flash Memory Summit

A classic case of SNIA Solid State Storage Initiative (SSSI) member collaboration for industry advancement was on display in the SSSI booth for NVDIMM-N demonstration at the Flash Memory Summit (FMS) 2015. Under the direction of SSSI Chair Jim Ryan and coordinated by NVDIMM SIG co chairs Arthur Sainio and Jeff Chang and TechDev Committee chair Eden Kim, the SSSI was able to update and include NVDIMM-N storage performance in the SSSI marketing collaterals on the Summary Performance Comparison by Storage Class charts.

2015SummaryPerformanceChart.NVDIMM.1200

Five SSSI member companies – AgigA Tech, Calypso, Micron, SMART Modular, and Viking Technology – collaborated over a four week period on the introduction of a new NVDIMM-N storage performance demonstration. While it is rare to have potential competitors collaborate in such a fashion, NVDIMM-N storage represents a new paradigm for super fast, low latency, high IO/watt storage solutions. The NVDIMM-SIG has taken a leadership position by evangelizing the technology and developing the industry infrastructure necessary for large scale deployment.

This collaboration highlighted a classic blend of technical, marketing and industry association cooperation.

In the weeks leading up to FMS, the NVDIMM-SIG planned for an in-booth demonstration of the NVDIMM-N storage modules. To pave the way for universal adoption, the team worked together to dial in the Intel Open Source block IO development driver to meet the standards of the SNIA Performance Test Specification (PTS). An added goal was inclusion of NVDIMM-N modules as a new line item on the Summary Performance Comparison by Storage Class chart which lists PTS performance for various storage technologies. Under the guidance of NVDIMM-SIG, a rush project was instigated to get NVDIMM-N performance data tested to the PTS for the trade show.

Micron took the lead by lending a Supermicro server with Micron NVDIMM-N to Calypso for testing. Calypso then installed CTS test software on the server to allow full testing to the PTS. Viking and SMART Modular contributed by helping dial in the drivers, as well as sending modules from Viking and SMART Modular to cross reference with the Micron modules. The test plan was comprised of several test iterations using single, dual and finally quad modules using each of the vendor contributed modules.

The early single and dual module tests ran into repeatability and stability issues. NVDIMM-SIG consulted with Intel on the nuance of the Intel block IO driver while Calypso continued testing. The team successfully completed a test run that met the PTS steady state requirements on the quad module in time to release data for the show.

We had a solid demonstration at the SNIA SSSI Flash Memory Summit Booth on NVDIMM-N Performance complete with marketing collateral available for review and a handout. NVDIMM-SIG members responded to the many questions and interest in the NVDIMM-N storage technology.

fms booth

“Once again,” said SSSI Chair Jim Ryan, “we can see the value and benefit of SNIA SSSI to its members, the SNIA educational community and the NVDIMM industry. I believe this is a great case study in how we all can contribute and benefit from working within the SSSI for the betterment of individual companies, market development and the Solid State Storage industry at large.” SSSI provides educational and marketing materials free of charge on its public website while SNIA SSSI members may join the NVDIMM-SIG and other SSSI committees. Anyone interested to find out more about the SSSI or any of its many committees can go to the following link http://www.snia.org/sssi.