Click here to close now.

Welcome!

Virtualization Authors: Liz McMillan, Pat Romanski, Carmen Gonzalez, Clinton Wolfe, AppDynamics Blog

Related Topics: Big Data Journal, Java, Open Source, Virtualization, Red Hat, Cloud Expo

Big Data Journal: Blog Feed Post

Big Data – Storage Mediums and Data Structures

Big Data presents something of a storage dilemma. There is no one data store to rule them all.

My working title was Big Data, Storage Dilemma.

They say dilemma. I say dilemna. I'm serious. I spell it dilemna.

Big Data presents something of a storage dilemma. There is no one data store to rule them all.

Should different data structures be persisted to different storage mediums?

Storage Medium
Identifying the appropriate medium is a function of performance, cost, and capacity.

Random Access Memory
It's fast. Very. It's expense. Very.

If we are configuring an HP DL980 G7 server, it will cost $3,672 for 128GB of memory with 8x 16GB modules or $9,996 for 128GB of memory with 4x 32GB modules. That is $28-78 / GB.

We can configure an HP DL980 G7 server with up to 4TB of memory.

Solid State Drive
It's not as fast or as expensive as random access memory. It's faster than a hard disk drive. A lot faster. It's more expensive than a hard disk drive. A lot more expensive.

If we are configuring an HP DL980 G7 server, it will cost $4,199 for a 400GB SAS MLC drive or $7,419 for a 400GB SAS SLC drive. That is $10-18 / GB. It's a performance / size trade-off. While SLC drives often perform better, MLC drives are often available in larger sizes. Further, the read / write performance is either symmetric or asymmetric.

That, and SLC drives often have greater endurance.


Sequential
Read
(MB/s)
Sequential
Write
(MB/s)
Random
Read
(IOPS)
Random
Write
(IOPS)
Intel 520 (480GB) 550 520 50,000 50,000
Intel 520 (240GB) 550 520 50,000 80,000
Intel DC S3700 500 460 75,000 36,000

The performance of solid state drives can vary:

  • consumer / enterprise
  • MLC / eMLC / SLC
  • SATA / SAS / PCIe

The capacity of enterprise solid state drives is often less than that of enterprise hard disk drives (4TB). However, the capacity of PCIe drives such as the Fusion-io ioDrive Octal (5.12TB / 10.24TB) is greater than that of enterprise hard disk drives (4TB). In addition, the performance of PCIe drives is greater than that of SAS or SATA drives.


Sequential
Read
(MB/s)
Sequential
Write
(MB/s)
Random
Read
(IOPS)
Random
Write
(IOPS)
Intel 910 (800GB) 2,000 1,000 180,000 75,000

Hard Disk Drive

It may not be fast, but it is inexpensive.

If we are configuring an HP DL980 G7 server, it will cost $309 for a 300GB 10K drive or $649 for a 300GB 15K drive. That is $1-2 / GB. It's a performance / size trade-off. While a 15K drive will perform better than a 10K drive, it will often have less capacity. The sequential read / write performance of hard disk drives is often between 150-200MB/s. As such, a RAID configuration may be a cost effective alternative to a single solid state drive for sequential read / write access.

The capacity of enterprise hard disk drives (4TB) is often greater than that of enterprise solid state drives.

Data Structure
Hash Table

JBoss Data Grid is an in-memory data grid with the data stored in a hash table. However, JBoss Data Grid supports persistence via write-behind or write-through. For all intents and purposes (e.g. map / reduce), all of the data should fit in memory.

Access

  • Random Reads, Random Writes

Riak is a key / value store. If persistence has been configured with Bitcast, the data is stored in a log structured hash table. An in-memory hash table contains the key / value pointers. The value is a pointer to the data. As such, all of the key / value pointers must fit in memory. The data is persisted via append only log files.

Access

  • Complex Index in Memory
  • Random Reads, Sequential Writes

Point queries perform well in hash tables. Range queries do not. Though there is always map / reduce.

B-Tree
MongoDB is a document database with the data stored in a B-Tree. The data is persisted via memory mapped files.

Access

  • Partial Index (Internal Nodes) in Memory
  • Random Reads, Sequential Reads, Random Writes

CouchDB is a document database with the data stored in a B+Tree. The data is persisted via append only log files.

Access

  • Partial Index in Memory
  • Random Reads, Sequential Reads, Sequential Writes

In a B+ Tree, the data is only stored in the leaf nodes. In a B-Tree, the data is stored in both the internal nodes and the leaf nodes. The advantage of a B+ Tree is that the leaf nodes are linked. As a result, range queries perform better with a B+ Tree. However, point queries perform better with a B-Tree.

CouchDB has implemented an append only B+ Tree. An alternative is the copy-on-write (CoW) B+ Tree. A write optimization for a B-Tree is buffering. First, the data written to an internal buffer in an internal node. Second, the buffer is flushed to a leaf node. As a result, random writes are turned in to sequential writes. The cost of random writes is thus amortized.  However, I am not aware of any open source data stores that have implemented a CoW B+ Tree or have implemented buffering with a B-Tree.

Range queries perform well with a B/B+ Tree. Point queries, not as well as hash tables.

Log Structured Merge Tree
Apache HBase and Apache Cassandra are both column oriented data stores, and they have both store data in an LSM-Tree. Apache HBase has implemented a cache oblivious lookahead array (COLA). Apache Cassandra has implemented a sorted array merge tree (SAMT).

In both implementations, a write is first written to a write-ahead log. Next, it is written to a memtable. A memtable is an in-memory sorted string table (SSTable). Later, the memtable is flushed and persisted as an SSTable. As result, random writes are turned in to sequential writes. However, a point query with an LSM-Tree may require multiple random reads.

Apache HBase implemented a single-level index with HFile version 1. However, because every index was cached, it resulted in high memory usage.

Apache HBase implemented a multi-level index a la a B+ Tree with HFile (SSTable) version 2. The SSTable contains a root index, a root index with leaf indexes, or a root index with an intermediate index and leaf indexes. The root index is stored in memory. The intermediate and leaf indexes may be stored in the block cache. In addition, the SSTable contains a compound (block level) bloom filter. The bloom filter is used to determine if the data is not in the data block.

Recommendation / Access

  • Partial Index / Bloom Filter in Memory
  • Random Reads, Sequential Reads, Sequential Writes

A read optimization for an LSM-Tree is fractional cascading. The idea is that each level contains both data and pointers to data in the next level. However, I am not aware of any open source data stores that have implemented fractional cascading.

I like the idea of a hybrid / tiered storage solution for an LSM-Tree implementation with the first level in memory, second level on solid state drives, and third level on hard disk drives. I've seen this solution described in academia, but I am not aware of any open source implementations.

Conclusion
I find it interesting that key / value stores often store data in a hash table, that document stores often store data in a B+/B-Tree, and that column oriented stores often store data in an LSM-Tree. Perhaps it is because key / value stores focus on the performance of point queries, document stores support secondary indexes (MongoDB) / views  (CouchDB), and column oriented stores support range queries. Perhaps it because document stores were not created with distribution (shards / partitions) in mind and thus assume that the complete index can not be stored in memory.

Notes
I found this paper to be very helpful in examining data structures as it covers most of the ones highlighted in this post:

Efficient, Scalable, and Versatile Application and System Transaction Management for Direct Storage Layers (link)

Read the original blog entry...

More Stories By Daniel Thompson

I curate the content on this page, but the credit goes to my talented colleagues for the posts that you see here. Much of what you read on this page is the work of friends at How to JBoss, and I encourage you to drop by the site at http://www.howtojboss.com for some of the best JBoss technical and non-technical content for developers, architects and technology executives on the Web.

@ThingsExpo Stories
Sensor-enabled things are becoming more commonplace, precursors to a larger and more complex framework that most consider the ultimate promise of the IoT: things connecting, interacting, sharing, storing, and over time perhaps learning and predicting based on habits, behaviors, location, preferences, purchases and more. In his session at @ThingsExpo, Tom Wesselman, Director of Communications Ecosystem Architecture at Plantronics, will examine the still nascent IoT as it is coalescing, including what it is today, what it might ultimately be, the role of wearable tech, and technology gaps stil...
Almost everyone sees the potential of Internet of Things but how can businesses truly unlock that potential. The key will be in the ability to discover business insight in the midst of an ocean of Big Data generated from billions of embedded devices via Systems of Discover. Businesses will also need to ensure that they can sustain that insight by leveraging the cloud for global reach, scale and elasticity.
The Internet of Things (IoT) promises to evolve the way the world does business; however, understanding how to apply it to your company can be a mystery. Most people struggle with understanding the potential business uses or tend to get caught up in the technology, resulting in solutions that fail to meet even minimum business goals. In his session at @ThingsExpo, Jesse Shiah, CEO / President / Co-Founder of AgilePoint Inc., showed what is needed to leverage the IoT to transform your business. He discussed opportunities and challenges ahead for the IoT from a market and technical point of vie...
IoT is still a vague buzzword for many people. In his session at @ThingsExpo, Mike Kavis, Vice President & Principal Cloud Architect at Cloud Technology Partners, discussed the business value of IoT that goes far beyond the general public's perception that IoT is all about wearables and home consumer services. He also discussed how IoT is perceived by investors and how venture capitalist access this space. Other topics discussed were barriers to success, what is new, what is old, and what the future may hold. Mike Kavis is Vice President & Principal Cloud Architect at Cloud Technology Pa...
Hadoop as a Service (as offered by handful of niche vendors now) is a cloud computing solution that makes medium and large-scale data processing accessible, easy, fast and inexpensive. In his session at Big Data Expo, Kumar Ramamurthy, Vice President and Chief Technologist, EIM & Big Data, at Virtusa, will discuss how this is achieved by eliminating the operational challenges of running Hadoop, so one can focus on business growth. The fragmented Hadoop distribution world and various PaaS solutions that provide a Hadoop flavor either make choices for customers very flexible in the name of opti...
The true value of the Internet of Things (IoT) lies not just in the data, but through the services that protect the data, perform the analysis and present findings in a usable way. With many IoT elements rooted in traditional IT components, Big Data and IoT isn’t just a play for enterprise. In fact, the IoT presents SMBs with the prospect of launching entirely new activities and exploring innovative areas. CompTIA research identifies several areas where IoT is expected to have the greatest impact.
The Internet of Things (IoT) is rapidly in the process of breaking from its heretofore relatively obscure enterprise applications (such as plant floor control and supply chain management) and going mainstream into the consumer space. More and more creative folks are interconnecting everyday products such as household items, mobile devices, appliances and cars, and unleashing new and imaginative scenarios. We are seeing a lot of excitement around applications in home automation, personal fitness, and in-car entertainment and this excitement will bleed into other areas. On the commercial side, m...
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 expertise to guard against those threats. But will that be enough? In the foreseeable future attacks w...
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 supplier management. Learn about enterprise architecture strategies for designing connected systems tha...
Dale Kim is the Director of Industry Solutions at MapR. His background includes a variety of technical and management roles at information technology companies. While his experience includes work with relational databases, much of his career pertains to non-relational data in the areas of search, content management, and NoSQL, and includes senior roles in technical marketing, sales engineering, and support engineering. Dale holds an MBA from Santa Clara University, and a BA in Computer Science from the University of California, Berkeley.
Wearable devices have come of age. The primary applications of wearables so far have been "the Quantified Self" or the tracking of one's fitness and health status. We propose the evolution of wearables into social and emotional communication devices. Our BE(tm) sensor uses light to visualize the skin conductance response. Our sensors are very inexpensive and can be massively distributed to audiences or groups of any size, in order to gauge reactions to performances, video, or any kind of presentation. In her session at @ThingsExpo, Jocelyn Scheirer, CEO & Founder of Bionolux, will discuss ho...
The cloud is now a fact of life but generating recurring revenues that are driven by solutions and services on a consumption model have been hard to implement, until now. In their session at 16th Cloud Expo, Ermanno Bonifazi, CEO & Founder of Solgenia, and Ian Khan, Global Strategic Positioning & Brand Manager at Solgenia, will discuss how a top European telco has leveraged the innovative recurring revenue generating capability of the consumption cloud to enable a unique cloud monetization model to drive results.
As organizations shift toward IT-as-a-service models, the need for managing and protecting data residing across physical, virtual, and now cloud environments grows with it. CommVault can ensure protection &E-Discovery of your data – whether in a private cloud, a Service Provider delivered public cloud, or a hybrid cloud environment – across the heterogeneous enterprise. In his session at 16th Cloud Expo, Randy De Meno, Chief Technologist - Windows Products and Microsoft Partnerships, will discuss how to cut costs, scale easily, and unleash insight with CommVault Simpana software, the only si...
Docker is an excellent platform for organizations interested in running microservices. It offers portability and consistency between development and production environments, quick provisioning times, and a simple way to isolate services. In his session at DevOps Summit at 16th Cloud Expo, Shannon Williams, co-founder of Rancher Labs, will walk through these and other benefits of using Docker to run microservices, and provide an overview of RancherOS, a minimalist distribution of Linux designed expressly to run Docker. He will also discuss Rancher, an orchestration and service discovery platf...
Analytics is the foundation of smart data and now, with the ability to run Hadoop directly on smart storage systems like Cloudian HyperStore, enterprises will gain huge business advantages in terms of scalability, efficiency and cost savings as they move closer to realizing the potential of the Internet of Things. In his session at 16th Cloud Expo, Paul Turner, technology evangelist and CMO at Cloudian, Inc., will discuss the revolutionary notion that the storage world is transitioning from mere Big Data to smart data. He will argue that today’s hybrid cloud storage solutions, with commodity...
Cloud data governance was previously an avoided function when cloud deployments were relatively small. With the rapid adoption in public cloud – both rogue and sanctioned, it’s not uncommon to find regulated data dumped into public cloud and unprotected. This is why enterprises and cloud providers alike need to embrace a cloud data governance function and map policies, processes and technology controls accordingly. In her session at 15th Cloud Expo, Evelyn de Souza, Data Privacy and Compliance Strategy Leader at Cisco Systems, will focus on how to set up a cloud data governance program and s...
Roberto Medrano, Executive Vice President at SOA Software, had reached 30,000 page views on his home page - http://RobertoMedrano.SYS-CON.com/ - on the SYS-CON family of online magazines, which includes Cloud Computing Journal, Internet of Things Journal, Big Data Journal, and SOA World Magazine. He is a recognized executive in the information technology fields of SOA, internet security, governance, and compliance. He has extensive experience with both start-ups and large companies, having been involved at the beginning of four IT industries: EDA, Open Systems, Computer Security and now SOA.
Every innovation or invention was originally a daydream. You like to imagine a “what-if” scenario. And with all the attention being paid to the so-called Internet of Things (IoT) you don’t have to stretch the imagination too much to see how this may impact commercial and homeowners insurance. We’re beyond the point of accepting this as a leap of faith. The groundwork is laid. Now it’s just a matter of time. We can thank the inventors of smart thermostats for developing a practical business application that everyone can relate to. Gone are the salad days of smart home apps, the early chalkb...
The industrial software market has treated data with the mentality of “collect everything now, worry about how to use it later.” We now find ourselves buried in data, with the pervasive connectivity of the (Industrial) Internet of Things only piling on more numbers. There’s too much data and not enough information. In his session at @ThingsExpo, Bob Gates, Global Marketing Director, GE’s Intelligent Platforms business, to discuss how realizing the power of IoT, software developers are now focused on understanding how industrial data can create intelligence for industrial operations. Imagine ...
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 of our infrastructures. At the same time, we have old approaches made new again like micro-services...