Welcome!

Related Topics: Containers Expo Blog, Microservices Expo, Microsoft Cloud, Linux Containers, Cloud Security, SDN Journal

Containers Expo Blog: 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.


Latest Stories
In this strange new world where more and more power is drawn from business technology, companies are effectively straddling two paths on the road to innovation and transformation into digital enterprises. The first path is the heritage trail – with “legacy” technology forming the background. Here, extant technologies are transformed by core IT teams to provide more API-driven approaches. Legacy systems can restrict companies that are transitioning into digital enterprises. To truly become a lead...
Companies are harnessing data in ways we once associated with science fiction. Analysts have access to a plethora of visualization and reporting tools, but considering the vast amount of data businesses collect and limitations of CPUs, end users are forced to design their structures and systems with limitations. Until now. As the cloud toolkit to analyze data has evolved, GPUs have stepped in to massively parallel SQL, visualization and machine learning.
DevOps at Cloud Expo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to w...
SYS-CON Events announced today that Daiya Industry will exhibit at the Japanese Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Ruby Development Inc. builds new services in short period of time and provides a continuous support of those services based on Ruby on Rails. For more information, please visit https://github.com/RubyDevInc.
When it comes to cloud computing, the ability to turn massive amounts of compute cores on and off on demand sounds attractive to IT staff, who need to manage peaks and valleys in user activity. With cloud bursting, the majority of the data can stay on premises while tapping into compute from public cloud providers, reducing risk and minimizing need to move large files. In his session at 18th Cloud Expo, Scott Jeschonek, Director of Product Management at Avere Systems, discussed the IT and busine...
As businesses evolve, they need technology that is simple to help them succeed today and flexible enough to help them build for tomorrow. Chrome is fit for the workplace of the future — providing a secure, consistent user experience across a range of devices that can be used anywhere. In her session at 21st Cloud Expo, Vidya Nagarajan, a Senior Product Manager at Google, will take a look at various options as to how ChromeOS can be leveraged to interact with people on the devices, and formats th...
First generation hyperconverged solutions have taken the data center by storm, rapidly proliferating in pockets everywhere to provide further consolidation of floor space and workloads. These first generation solutions are not without challenges, however. In his session at 21st Cloud Expo, Wes Talbert, a Principal Architect and results-driven enterprise sales leader at NetApp, will discuss how the HCI solution of tomorrow will integrate with the public cloud to deliver a quality hybrid cloud e...
Is advanced scheduling in Kubernetes achievable? Yes, however, how do you properly accommodate every real-life scenario that a Kubernetes user might encounter? How do you leverage advanced scheduling techniques to shape and describe each scenario in easy-to-use rules and configurations? In his session at @DevOpsSummit at 21st Cloud Expo, Oleg Chunikhin, CTO at Kublr, will answer these questions and demonstrate techniques for implementing advanced scheduling. For example, using spot instances ...
SYS-CON Events announced today that Yuasa System will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Yuasa System is introducing a multi-purpose endurance testing system for flexible displays, OLED devices, flexible substrates, flat cables, and films in smartphones, wearables, automobiles, and healthcare.
SYS-CON Events announced today that Taica will exhibit at the Japan External Trade Organization (JETRO) Pavilion at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Taica manufacturers Alpha-GEL brand silicone components and materials, which maintain outstanding performance over a wide temperature range -40C to +200C. For more information, visit http://www.taica.co.jp/english/.
As hybrid cloud becomes the de-facto standard mode of operation for most enterprises, new challenges arise on how to efficiently and economically share data across environments. In his session at 21st Cloud Expo, Dr. Allon Cohen, VP of Product at Elastifile, will explore new techniques and best practices that help enterprise IT benefit from the advantages of hybrid cloud environments by enabling data availability for both legacy enterprise and cloud-native mission critical applications. By rev...
When it comes to cloud computing, the ability to turn massive amounts of compute cores on and off on demand sounds attractive to IT staff, who need to manage peaks and valleys in user activity. With cloud bursting, the majority of the data can stay on premises while tapping into compute from public cloud providers, reducing risk and minimizing need to move large files. In his session at 18th Cloud Expo, Scott Jeschonek, Director of Product Management at Avere Systems, discussed the IT and busine...
Organizations do not need a Big Data strategy; they need a business strategy that incorporates Big Data. Most organizations lack a road map for using Big Data to optimize key business processes, deliver a differentiated customer experience, or uncover new business opportunities. They do not understand what’s possible with respect to integrating Big Data into the business model.
Recently, REAN Cloud built a digital concierge for a North Carolina hospital that had observed that most patient call button questions were repetitive. In addition, the paper-based process used to measure patient health metrics was laborious, not in real-time and sometimes error-prone. In their session at 21st Cloud Expo, Sean Finnerty, Executive Director, Practice Lead, Health Care & Life Science at REAN Cloud, and Dr. S.P.T. Krishnan, Principal Architect at REAN Cloud, will discuss how they b...
Enterprises have taken advantage of IoT to achieve important revenue and cost advantages. What is less apparent is how incumbent enterprises operating at scale have, following success with IoT, built analytic, operations management and software development capabilities – ranging from autonomous vehicles to manageable robotics installations. They have embraced these capabilities as if they were Silicon Valley startups. As a result, many firms employ new business models that place enormous impor...