Welcome!

SDN Journal Authors: Marten Terpstra, Liz McMillan, Elizabeth White, Michael Jannery, Tom Scearce

Related Topics: Virtualization, SOA & WOA, .NET, Linux, Security, SDN Journal

Virtualization: Article

Data Efficiency at Scale

Overcoming limitations in data efficiency features

The initial wave of data efficiency features for primary storage focus on silos of information organized in terms of individual file systems. Deduplication and compression features provided by some vendors are limited by the scalability of those underlying file systems, essentially the file systems have become silos of optimized data. For example, NetApp deduplication can't scale beyond a 100 TB limit, because that's the limit in size of its WAFL file system. But ask anyone who's ever used NetApp deduplication if they've done it on a 100 TB file system, and you're likely to hear "are you crazy?" It's one thing to claim that data efficiency features can scale, quite a different one to actually use them with performance at scale.

Challenges around scalability generally center on two areas: scalability of random IO and memory overhead. Older solutions, like the one from NetApp, face the first challenge while newer flash-based storage systems are struggling with the second. I'll review both here:

The IO Challenge
Primary data-oriented storage devices handle both streaming and random throughput and therefore are sensitive to latency effects. Data efficiency requirements for primary storage must have fast hashing techniques to reduce the impact of latency. Fast hashes are non-cryptographic in nature and so require data comparison when used to do deduplication. It works like this:

  1. When a new chunk of data is read in it is first given a name using the hash algorithm.
  2. The system then checks a deduplication index to see if a chunk with that name has been seen before (note that this can consume disk IO and tremendous amounts of memory if done wrong).
  3. If the name has been seen we need to take extra steps. Because fast hashes are non-cryptographic, it is possible to have a name match while the data content differs. This is known in computer science as a hash-collision. To account for this, the existing copy of the chunk must be read in and compared bit-by-bit to the new. If they match, only a reference to the chunk is created. If not, then the new chunk must be written.

Essentially, this form of deduplication means trading a write of a duplicate chunk for a read. Depending on the design of the underlying block virtualization layer, duplicate chunks may be widely dispersed throughout the system. In that case, the bigger the system gets, the more expensive reads get - so processing of duplicate data becomes slower and slower as the storage system fills - this is why you won't find many 100 TB NetApp file systems with deduplication turned on. Certainly not for primary storage applications, the system would be flooded with random read requests and NetApp's deduplication process can end up taking months, years or even never complete.

A number of techniques have been used to reduce the impact of IO in other products. For example, the Hitachi NAS (HNAS) and Hitachi Unified Storage (HUS) solutions from HDS make use of hardware-acceleration to generate cryptographically secure hashes that do not require a data compare at all - this allows for linear scaling of deduplication performance on volumes up to 256 TB in size. Data is also written out before it is deduplicated to avoid introducing any latency through the hash computation process itself.

Permabit's own Albireo Virtual Data Optimizer (VDO) product, a plug-in module for Linux-based storage solutions, takes a different approach but with a similar result. VDO works inline to provide immediate data reduction. When data is written out, the VDO process intelligently lays it out in a sequential pattern, so that subsequent read compares of duplicates are more likely to be sequential as well. Both solutions do a fine job at solving the problem in real world scenarios, they just take different approaches.

The Memory Challenge
Many of today's flash array vendors are providing deduplication using similar fast hashing techniques to what I outlined above. With flash, the cost of doing random reads for read compares is a non-issue (random seeks on flash are much less expensive than for hard drive environments) so the use of the fast hash alone is enough to minimize latency. These systems (such as EMC's recently launched XtremIO product) are focused on delivering performance and the big challenge to performance at scale is available memory (DRAM). As above, after chunks are read in, they are named using a fast hashing algorithm. After that, the flash system must determine whether or not a chunk has been seen before. To get at this information as quickly as possible, flash-based storage systems have tended to use huge amounts of DRAM to cache chunk names in memory. It's not uncommon to see flash storage systems that allocate 16 GB of working cache per TB of storage. To support a 256 TB storage volume, such a system would require a TBs of DRAM. The increased hard costs in terms of more expensive (denser) DIMMS, as well as the increased cost of the server board required to support this many DIMMs combine to make this an extremely costly and unpopular proposition. Combine this with the fact that DRAM prices are not falling at the same rate as flash prices, and you can see why no vendor today makes a 256TB flash storage array with global deduplication capabilities.

The solution to the memory challenge is coming, in the form of a next generation of flash storage products that utilize Albireo indexing and Albireo VDO. Unlike the flash arrays described above, flash-optimized arrays with VDO takes advantage of advanced caching techniques to operate with 128 MB of working cache per TB of storage and deliver excellent performance. With VDO, a 256 TB system can be delivered with as little as 32 GB of RAM while delivering 1M IOPS performance. The net result is a cost effective and easily deployed data efficiency solution for flash arrays.

Conclusion

Deduplication Scalability by Vendor

As you can see in the table above, forward thinking vendors like HDS have done a good job at overcoming limitations in their data efficiency features and have products on the market today that can scale to meet the requirements of the large enterprise. Many other vendors are lagging behind, because of their inability to address IO and/or memory requirements, a serious downfall since data efficiency is at the core of distinguishing storage solutions, a critical end user requirement, and a ‘must have' component for 2014. Permabit's VDO product overcomes both of these limitations through the use of advanced memory-efficient caching techniques.

More Stories By Louis Imershein

As Senior Director of Product Strategy at Permabit Technology Corporation, Louis Imershein is responsible for product evolution and strategic planning for the Albireo family of products. He has 22 years of technical leadership experience in product management, software development and support. Prior to joining Permabit, Imershein was a Senior Product Marketing Manager for the Sun Microsystems Data Management Group. He has a Bachelor's degree in Biological Science from the University of California, Santa Cruz.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@CloudExpo Stories
CodeFutures has announced Dan Lynn as its new CEO. Lynn assumes the role from Founder Cory Isaacson, who has joined RMS and will now serve as chairman of CodeFutures. Lynn brings more than 14 years of advanced technology and business success experience, and will help CodeFutures build on its industry leadership around its Agile Big Data initiatives. His technical expertise will be invaluable in advancing CodeFutures’ AgilData platform and new processes for streamlining and gaining value from gro...
In this scenarios approach Joe Thykattil, Technology Architect & Sales at TimeWarner / Navisite, presented examples that will allow business-savvy professionals to make informed decisions based on a sound business model. This model covered the technology options in detail as well as a financial analysis. The TCO (Total Cost of Ownership) and ROI (Return on Investment) demonstrated how to start, develop and formulate a business case that will allow both small and large scale projects to achieve...
IBM has announced a new strategic technology services agreement with Anthem, Inc., a health benefits company in the U.S. IBM has been selected to provide operational services for Anthem's mainframe and data center server and storage infrastructure for the next five years. Among the benefits of the relationship, Anthem has the ability to leverage IBM Cloud solutions that will help increase the ease, availability and speed of adding infrastructure to support new business requirements.
SYS-CON Media announced that Cisco, a worldwide leader in IT that helps companies seize the opportunities of tomorrow, has launched a new ad campaign in Cloud Computing Journal. The ad campaign, a webcast titled 'Is Your Data Center Ready for the Application Economy?', focuses on the latest data center networking technologies, including SDN or ACI, and how customers are using SDN and ACI in their organizations to achieve business agility. The Cisco webcast is available on-demand.
Cloud and Big Data present unique dilemmas: embracing the benefits of these new technologies while maintaining the security of your organization's assets. When an outside party owns, controls and manages your infrastructure and computational resources, how can you be assured that sensitive data remains private and secure? How do you best protect data in mixed use cloud and big data infrastructure sets? Can you still satisfy the full range of reporting, compliance and regulatory requirements? In...
Advanced Persistent Threats (APTs) are increasing at an unprecedented rate. The threat landscape of today is drastically different than just a few years ago. Attacks are much more organized and sophisticated. They are harder to detect and even harder to anticipate. In the foreseeable future it's going to get a whole lot harder. Everything you know today will change. Keeping up with this changing landscape is already a daunting task. Your organization needs to use the latest tools, methods and ex...
Security can create serious friction for DevOps processes. We've come up with an approach to alleviate the friction and provide security value to DevOps teams. In her session at DevOps Summit, Shannon Lietz, Senior Manager of DevSecOps at Intuit, will discuss how DevSecOps got started and how it has evolved. Shannon Lietz has over two decades of experience pursuing next generation security solutions. She is currently the DevSecOps Leader for Intuit where she is responsible for setting and driv...
SYS-CON Events announced today that ActiveState, the leading independent Cloud Foundry and Docker-based PaaS provider, has been named “Silver Sponsor” of SYS-CON's DevOps Summit New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. ActiveState believes that enterprises gain a competitive advantage when they are able to quickly create, deploy and efficiently manage software solutions that immediately create business value, but they face many challenges that ...
Mobile commerce traffic is surpassing desktop, yet less than 20% of sales in the U.S. are mobile commerce sales. In his session at 15th Cloud Expo, Dan Franklin, Segment Manager, Commerce, at Verizon Digital Media Services, defined mobile devices and discussed how next generation means simplification. It means taking your digital content and turning it into instantly gratifying experiences.
Today’s enterprise is being driven by disruptive competitive and human capital requirements to provide enterprise application access through not only desktops, but also mobile devices. To retrofit existing programs across all these devices using traditional programming methods is very costly and time consuming – often prohibitively so. In his session at @ThingsExpo, Jesse Shiah, CEO, President, and Co-Founder of AgilePoint Inc., discussed how you can create applications that run on all mobile ...
From telemedicine to smart cars, digital homes and industrial monitoring, the explosive growth of IoT has created exciting new business opportunities for real time calls and messaging. In his session at @ThingsExpo, Ivelin Ivanov, CEO and Co-Founder of Telestax, shared some of the new revenue sources that IoT created for Restcomm – the open source telephony platform from Telestax. Ivelin Ivanov is a technology entrepreneur who founded Mobicents, an Open Source VoIP Platform, to help create, de...
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core...
Cloud services are the newest tool in the arsenal of IT products in the market today. These cloud services integrate process and tools. In order to use these products effectively, organizations must have a good understanding of themselves and their business requirements. In his session at 15th Cloud Expo, Brian Lewis, Principal Architect at Verizon Cloud, outlined key areas of organizational focus, and how to formalize an actionable plan when migrating applications and internal services to the ...
"SOASTA built the concept of cloud testing in 2008. It's grown from rather meager beginnings to where now we are provisioning hundreds of thousands of servers on a daily basis on behalf of customers around the world to test their applications," explained Tom Lounibos, CEO of SOASTA, in this SYS-CON.tv interview at DevOps Summit, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Disruptive macro trends in technology are impacting and dramatically changing the "art of the possible" relative to supply chain management practices through the innovative use of IoT, cloud, machine learning and Big Data to enable connected ecosystems of engagement. Enterprise informatics can now move beyond point solutions that merely monitor the past and implement integrated enterprise fabrics that enable end-to-end supply chain visibility to improve customer service delivery and optimize sup...
Vormetric on Wednesday announced the results of its 2015 Insider Threat Report (ITR), conducted online on their behalf by Harris Poll and in conjunction with analyst firm Ovum in fall 2014 among 818 IT decision makers in various countries, including 408 in the United States. The report details striking findings around how U.S. and international enterprises perceive security threats, the types of employees considered most dangerous, environments at the greatest risk for data loss and the steps or...
“DevOps is really about the business. The business is under pressure today, competitively in the marketplace to respond to the expectations of the customer. The business is driving IT and the problem is that IT isn't responding fast enough," explained Mark Levy, Senior Product Marketing Manager at Serena Software, in this SYS-CON.tv interview at DevOps Summit, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CodeFutures, a leading supplier of database performance tools, has been named a “Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. CodeFutures is an independent software vendor focused on providing tools that deliver database performance tools that increase productivity during database development and increase database performance and scalability during production.
"Verizon Digital Media Services is responsible for the broadcast, video and content delivery network that accelerates, scales and helps our customers reach end users with all kinds of video and web content," stated James Segil, CMO of Verizon Digital Media Services, in this SYS-CON.tv interview at 15th Cloud Expo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.
Docker is becoming very popular--we are seeing every major private and public cloud vendor racing to adopt it. It promises portability and interoperability, and is quickly becoming the currency of the Cloud. In his session at DevOps Summit, Bart Copeland, CEO of ActiveState, discussed why Docker is so important to the future of the cloud, but will also take a step back and show that Docker is actually only one piece of the puzzle. Copeland will outline the bigger picture of where Docker fits a...