Panasas Invents ‘Tiered Parity’

By Michael Feldman

October 12, 2007

In 1988 Garth Gibson at the University of California, Berkeley, co-authored a paper titled “A Case for Redundant Arrays of Inexpensive Disks (RAID) [PDF],” which outlined the basic principles of using big, cheap disks to increase data reliability and I/O performance. RAID went on to become a widely adopted storage technology throughout the industry, while Gibson co-founded Panasas Inc., a storage cluster vendor for high performance computing applications.

This week, Gibson and company claim that they have implemented the most significant extension to disk array data reliability since the original RAID paradigm was developed. Their new architecture is called “tiered parity.” In this model, Panasas has built “vertical parity” and “network parity” on top of their existing RAID 5 “horizontal parity” implementation.

The RAID 5 approach, as it was outlined in the original paper, consists of striping data and parity across multiple disks. It enables error recovery for single disk failures and increases performance via parallel reads and writes. This technology is widely used in storage systems today. Panasas’ own implementation of RAID 5, called “ObjectRAID,” is based on storage objects rather than blocks. The added intelligence is designed to reduce reconstruction times when a disk failure occurs.

But no RAID 5 technology can handle a media error, also know as an unrecoverable read error (URE), if it occurs during reconstruction of a failed disk. When this occurs, the RAID data cannot be rebuilt from disk; a backup (usually on tape) has to be used to recover the entire array. Ten years ago, this wasn’t a serious problem. With 50 GB SATA disk drives, a media error was very unlikely to occur while reading a single disk, since the rate of failure is about one error every 10^14 bits (12.5 terabytes), a rate that has remained constant for over a decade. And when a media error did happen to occur during reconstruction, a 50 GB disk took only a few hours to recover from tape.

Times have changed. Disks have become much bigger and denser. Capacities of 500 to 750 GB are common today, and one terabyte disks will soon be the norm. That means when a disk goes south, the odds of hitting a media error during recovery are much greater, and recovery from tape can take days or weeks.

Imagine a RAID array of seven 1 TB disks. When one disk fails, the chances of hitting a URE while recovering the data from the six remaining disks is now about 50/50. When two terabyte disks hit the market in 2009, the disk failure plus media error scenario becomes almost a sure bet. Recovering the storage array from backup tape could take a month. For high end computing applications that use tens or hundreds of terabytes of data, this would be a disaster.

“I think what people are becoming aware of is that the data integrity provided by RAID 5 is basically no longer sufficient,” says Robin Harris, senior analyst at Data Mobility Group. “RAID 5 will only protect across a single disk failure, so it’s going away as a [standalone] data protection strategy.”

To address this problem, Panasas invented vertical parity. Essentially, they’ve added RAID within each disk, by generating a parity sector from the other sectors. The local parity sector can be used to recompute the missing data in case of a media error. According to Panasas, vertical parity gets the error rate down to between one in 10^18 and one in 10^19, which is 1000 to 10,000 times better than the URE rate. The extra parity information uses 10 percent of the disk capacity, but Panasas claims there is no performance hit. So scalability is built in.

A word here should be said about RAID 6 technology (also known as double parity), which some vendors use for an additional level of data protection. This scheme was designed to guard against a double disk failure, which it does. Sort of. The problem is that RAID 6 doesn’t protect against subsequent media errors after the second disk goes down, which, as discussed above, is becoming increasingly more likely. Here, it has the same problem as RAID 5. However, RAID 6 can be used to recover from the single disk failure plus media error scenario. But the performance hit for dual parity compared to single parity is significant. So it’s a mixed bag and doesn’t directly address the media error problem.

On top of its horizonal and vertical parity schemes, Panasas has added an additional layer of network parity protection. At this level, parity checking is done on the client side, to make sure the data delivered by the storage system wasn’t corrupted on its way to the user. Because of increasing I/O bandwidth and the number of hardware and software components between the external data and the application, there are increasing opportunities for good data to go bad. Firmware, server hardware, server software, network components and transmission media can all potentially mangle valid data unbeknownst to the application. With network parity, the client receives an error notification when bad data is detected.

The tiered parity technology will be included in the next version of Panasas’ ActiveScale operating environment, version 3.2. The beta will be out next month and will be generally available by the end of the year. The additional parity levels can be turned off if the user believes they’re not needed for a particular environment. According to Panasas, the tiered parity technology doesn’t exact a performance hit on top of the existing RAID 5 implementation, but, as stated above, the vertical scheme does eat an additional 10 percent of the storage — that’s in addition to the 10 percent used by the RAID 5 implementation.

Although the overall concepts of the three-tiered architecture are fairly general, Panasas is attempting to protect its new invention. “We actually have a patent pending on this tiered parity concept, particularly the vertical parity,” says Larry Jones, VP of Marketing at Panasas. “Could someone copy it? Who knows? But we are trying to protect this specific idea.”

Subscribe to HPCwire's Weekly Update!

Be the most informed person in the room! Stay ahead of the tech trends with industy updates delivered to you every week!

Hyperion: AI-driven HPC Industry Continues to Push Growth Projections

November 21, 2019

Three major forces – AI, cloud and exascale – are combining to raise the HPC industry to heights exceeding expectations. According to market study results released this week by Hyperion Research at SC19 in Denver, Read more…

By Doug Black

At SC19: Bespoke Supercomputing for Climate and Weather

November 20, 2019

Weather and climate applications are some of the most important uses of HPC – a good model can save lives, as well as billions of dollars. But many weather and climate models struggle to run efficiently in their HPC en Read more…

By Oliver Peckham

Microsoft, Nvidia Launch Cloud HPC Service

November 20, 2019

Nvidia and Microsoft have joined forces to offer a cloud HPC capability based on the GPU vendor’s V100 Tensor Core chips linked via an InfiniBand network scaling up to 800 graphics processors. The partners announced Read more…

By George Leopold

Hazra Retiring from Intel Data Center Group, Successor Not Known

November 20, 2019

Rajeeb Hazra, corporate VP of Intel’s Data Center Group and GM for the Enterprise and Government Group, is retiring after more than 24 years at the company. At this writing, his successor is unknown. An earlier story on... Read more…

By Doug Black

Jensen Huang’s SC19 – Fast Cars, a Strong Arm, and Aiming for the Cloud(s)

November 20, 2019

We’ve come to expect Nvidia CEO Jensen Huang’s annual SC keynote to contain stunning graphics and lively bravado (with plenty of examples) in support of GPU-accelerated computing. In recent years, AI has joined the s Read more…

By John Russell

AWS Solution Channel

Making High Performance Computing Affordable and Accessible for Small and Medium Businesses with HPC on AWS

High performance computing (HPC) brings a powerful set of tools to a broad range of industries, helping to drive innovation and boost revenue in finance, genomics, oil and gas extraction, and other fields. Read more…

IBM Accelerated Insights

Data Management – The Key to a Successful AI Project

 

Five characteristics of an awesome AI data infrastructure

[Attend the IBM LSF & HPC User Group Meeting at SC19 in Denver on November 19!]

AI is powered by data

While neural networks seem to get all the glory, data is the unsung hero of AI projects – data lies at the heart of everything from model training to tuning to selection to validation. Read more…

SC19 Student Cluster Competition: Know Your Teams

November 19, 2019

I’m typing this live from Denver, the location of the 2019 Student Cluster Competition… and, oh yeah, the annual SC conference too. The attendance this year should be north of 13,000 people, with the majority attende Read more…

By Dan Olds

Hyperion: AI-driven HPC Industry Continues to Push Growth Projections

November 21, 2019

Three major forces – AI, cloud and exascale – are combining to raise the HPC industry to heights exceeding expectations. According to market study results r Read more…

By Doug Black

At SC19: Bespoke Supercomputing for Climate and Weather

November 20, 2019

Weather and climate applications are some of the most important uses of HPC – a good model can save lives, as well as billions of dollars. But many weather an Read more…

By Oliver Peckham

Hazra Retiring from Intel Data Center Group, Successor Not Known

November 20, 2019

Rajeeb Hazra, corporate VP of Intel’s Data Center Group and GM for the Enterprise and Government Group, is retiring after more than 24 years at the company. At this writing, his successor is unknown. An earlier story on... Read more…

By Doug Black

Jensen Huang’s SC19 – Fast Cars, a Strong Arm, and Aiming for the Cloud(s)

November 20, 2019

We’ve come to expect Nvidia CEO Jensen Huang’s annual SC keynote to contain stunning graphics and lively bravado (with plenty of examples) in support of GPU Read more…

By John Russell

Top500: US Maintains Performance Lead; Arm Tops Green500

November 18, 2019

The 54th Top500, revealed today at SC19, is a familiar list: the U.S. Summit (ORNL) and Sierra (LLNL) machines, offering 148.6 and 94.6 petaflops respectively, Read more…

By Tiffany Trader

ScaleMatrix and Nvidia Launch ‘Deploy Anywhere’ DGX HPC and AI in a Controlled Enclosure

November 18, 2019

HPC and AI in a phone booth: ScaleMatrix and Nvidia announced today at the SC19 conference in Denver a joint offering that puts up to 13 petaflops of Nvidia DGX Read more…

By Doug Black

Intel Debuts New GPU – Ponte Vecchio – and Outlines Aspirations for oneAPI

November 17, 2019

Intel today revealed a few more details about its forthcoming Xe line of GPUs – the top SKU is named Ponte Vecchio and will be used in Aurora, the first plann Read more…

By John Russell

SC19: Welcome to Denver

November 17, 2019

A significant swath of the HPC community has come to Denver for SC19, which began today (Sunday) with a rich technical program. As is customary, the ribbon cutt Read more…

By Tiffany Trader

Supercomputer-Powered AI Tackles a Key Fusion Energy Challenge

August 7, 2019

Fusion energy is the Holy Grail of the energy world: low-radioactivity, low-waste, zero-carbon, high-output nuclear power that can run on hydrogen or lithium. T Read more…

By Oliver Peckham

Using AI to Solve One of the Most Prevailing Problems in CFD

October 17, 2019

How can artificial intelligence (AI) and high-performance computing (HPC) solve mesh generation, one of the most commonly referenced problems in computational engineering? A new study has set out to answer this question and create an industry-first AI-mesh application... Read more…

By James Sharpe

Cray Wins NNSA-Livermore ‘El Capitan’ Exascale Contract

August 13, 2019

Cray has won the bid to build the first exascale supercomputer for the National Nuclear Security Administration (NNSA) and Lawrence Livermore National Laborator Read more…

By Tiffany Trader

DARPA Looks to Propel Parallelism

September 4, 2019

As Moore’s law runs out of steam, new programming approaches are being pursued with the goal of greater hardware performance with less coding. The Defense Advanced Projects Research Agency is launching a new programming effort aimed at leveraging the benefits of massive distributed parallelism with less sweat. Read more…

By George Leopold

AMD Launches Epyc Rome, First 7nm CPU

August 8, 2019

From a gala event at the Palace of Fine Arts in San Francisco yesterday (Aug. 7), AMD launched its second-generation Epyc Rome x86 chips, based on its 7nm proce Read more…

By Tiffany Trader

D-Wave’s Path to 5000 Qubits; Google’s Quantum Supremacy Claim

September 24, 2019

On the heels of IBM’s quantum news last week come two more quantum items. D-Wave Systems today announced the name of its forthcoming 5000-qubit system, Advantage (yes the name choice isn’t serendipity), at its user conference being held this week in Newport, RI. Read more…

By John Russell

Ayar Labs to Demo Photonics Chiplet in FPGA Package at Hot Chips

August 19, 2019

Silicon startup Ayar Labs continues to gain momentum with its DARPA-backed optical chiplet technology that puts advanced electronics and optics on the same chip Read more…

By Tiffany Trader

Crystal Ball Gazing: IBM’s Vision for the Future of Computing

October 14, 2019

Dario Gil, IBM’s relatively new director of research, painted a intriguing portrait of the future of computing along with a rough idea of how IBM thinks we’ Read more…

By John Russell

Leading Solution Providers

ISC 2019 Virtual Booth Video Tour

CRAY
CRAY
DDN
DDN
DELL EMC
DELL EMC
GOOGLE
GOOGLE
ONE STOP SYSTEMS
ONE STOP SYSTEMS
PANASAS
PANASAS
VERNE GLOBAL
VERNE GLOBAL

Cray, Fujitsu Both Bringing Fujitsu A64FX-based Supercomputers to Market in 2020

November 12, 2019

The number of top-tier HPC systems makers has shrunk due to a steady march of M&A activity, but there is increased diversity and choice of processing compon Read more…

By Tiffany Trader

Intel Confirms Retreat on Omni-Path

August 1, 2019

Intel Corp.’s plans to make a big splash in the network fabric market for linking HPC and other workloads has apparently belly-flopped. The chipmaker confirmed to us the outlines of an earlier report by the website CRN that it has jettisoned plans for a second-generation version of its Omni-Path interconnect... Read more…

By Staff report

Kubernetes, Containers and HPC

September 19, 2019

Software containers and Kubernetes are important tools for building, deploying, running and managing modern enterprise applications at scale and delivering enterprise software faster and more reliably to the end user — while using resources more efficiently and reducing costs. Read more…

By Daniel Gruber, Burak Yenier and Wolfgang Gentzsch, UberCloud

Dell Ramps Up HPC Testing of AMD Rome Processors

October 21, 2019

Dell Technologies is wading deeper into the AMD-based systems market with a growing evaluation program for the latest Epyc (Rome) microprocessors from AMD. In a Read more…

By John Russell

Rise of NIH’s Biowulf Mirrors the Rise of Computational Biology

July 29, 2019

The story of NIH’s supercomputer Biowulf is fascinating, important, and in many ways representative of the transformation of life sciences and biomedical res Read more…

By John Russell

Xilinx vs. Intel: FPGA Market Leaders Launch Server Accelerator Cards

August 6, 2019

The two FPGA market leaders, Intel and Xilinx, both announced new accelerator cards this week designed to handle specialized, compute-intensive workloads and un Read more…

By Doug Black

Intel Debuts New GPU – Ponte Vecchio – and Outlines Aspirations for oneAPI

November 17, 2019

Intel today revealed a few more details about its forthcoming Xe line of GPUs – the top SKU is named Ponte Vecchio and will be used in Aurora, the first plann Read more…

By John Russell

When Dense Matrix Representations Beat Sparse

September 9, 2019

In our world filled with unintended consequences, it turns out that saving memory space to help deal with GPU limitations, knowing it introduces performance pen Read more…

By James Reinders

  • arrow
  • Click Here for More Headlines
  • arrow
Do NOT follow this link or you will be banned from the site!
Share This