• Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Home
  • About
    • Stephen Foskett
      • My Publications
        • Urban Forms in Suburbia: The Rise of the Edge City
      • Storage Magazine Columns
      • Whitepapers
      • Multimedia
      • Speaking Engagements
    • Services
    • Disclosures
  • Categories
    • Apple
    • Ask a Pack Rat
    • Computer History
    • Deals
    • Enterprise storage
    • Events
    • Personal
    • Photography
    • Terabyte home
    • Virtual Storage
  • Guides
    • The iPhone Exchange ActiveSync Guide
      • The iPhone Exchange ActiveSync Troubleshooting Guide
    • The iPad Exchange ActiveSync Guide
      • iPad Exchange ActiveSync Troubleshooting Guide
    • Toolbox
      • Power Over Ethernet Calculator
      • EMC Symmetrix WWN Calculator
      • EMC Symmetrix TimeFinder DOS Batch File
    • Linux Logical Volume Manager Walkthrough
  • Calendar

Stephen Foskett, Pack Rat

Understanding the accumulation of data

You are here: Home / Everything / Are 320 GB Drives Doomed?

Are 320 GB Drives Doomed?

August 11, 2010 By Stephen 1 Comment

Ask a Pack Rat:

Reader Roger Pelizzari asks,

Enjoyed your detailed review of the Mac Mini. I got the late 2009 version.

What concerns me about the 320gb hard drive isn’t so much it’s slow speed as it’s reliability. I just read an article about 2.5 hard drives and the following paragraph gave me pause.

Any cheap 2.5” harddisk of 320GB or above is unreliable by definition. That’s just physics.

Data density for this small platter is so high (when over 125GB per platter), it’s reached the point after which the drive’s firmware relies heavily on ECC or other error correction methods. Your data is on a brink of becoming unreadable. Always use a business class drive if you need 320GB or higher in a laptop or 500GB in a desktop. If the hard disk is below 320GB, a mainstream drive is OK.

So what do you think. Is this 320GB drive in the Mini doomed?

Stephen’s Stance

I don’t think we can draw a line at 320 GB, but it’s certainly true that higher disk density increases the reliance on error correction and thus the risk of data loss. My friend Robin Harris talked about this just last month on ZDNet. Industry numbers suggest that one would have to fill a 320 GB SATA drive 37 times before encountering an unrecoverable read error, potentially losing data. This Microsoft test suggests that drives might be 10x more reliable than this, but that controllers and software above the drive are equally critical.

The Bit Error Rate (BER) for consumer SATA drives averages 1 in 1014. This means that for every 12.5 TB written, one unrecoverable read error (URE) will be encountered. Since it takes about an hour to write 1 GB to a consumer-grade drive, it would take on average 12,500 hours (520 days) to write enough data to encounter a URE.

Real-world applications don’t write anywhere near this much data, so the chance of a URE is much lower. As a rule of thumb, an average hard disk drive will be filled only once in its lifetime, leading to a shorthand calculation where 12.5 TB / (drive capacity) = chance of URE.

Therefore, I’d say that unrecoverable read errors aren’t yet at a crisis point for 320 GB drives. Whole-drive failure is much, much more likely. But drives are getting bigger all the time, and will soon reach the point where URE is inevitable. At current specs, filling a 1 TB drive has a 1 in 12 chance of URE, a 2 TB drive 1 in 6, and so on. RAID and other data integrity solutions will become an absolute necessity very soon, and even single-drive redundancy becomes problematic as drives near the 12 TB mark.

Parity RAID protects against URE by calculating a checksum for all data and recalculating the data if an error is detected. As long as the parity drive is running, two drives would have to hit a URE on the same data at the same time, an extremely remote occurrence.

But the risk of a URE in a RAID-5 set when one drive has failed is equal to the sum of the URE risk for the remaining drives, just like a non-protected set of drives that is one drive smaller. So a RAID-5 set consisting of 4 1.5 TB drives, once one drive has failed, is equal to the URE risk of a hypothetical 4.5 TB drive (3 x 1.5 TB), or one in 2.7. This is why dual-parity RAID-6 and other erasure code schemes are so valuable – they all but eliminate the chance of a URE for reasonably-sized drive and sets.

That’s why I’m a strong advocate of backups (thank you, Time Machine!) and RAID (thanks, Drobo!) Even today, with URE a fairly small concern, drive failures and data loss do happen. And these become more likely with motion (portable drives?) heat (planes and cars?) vibration (ibid) and other environmental conditions. Don’t panic about using 320 GB drives, but do back up your data anyway!

You might also want to read these other posts...

  • Electric Car Over the Internet: My Experience Buying From…
  • Liberate Wi-Fi Smart Bulbs and Switches with Tasmota!
  • How To Install ZeroTier on TrueNAS 12
  • Tortoise or Hare? Nvidia Jetson TK1
  • Introducing Rabbit: I Bought a Cloud!

Filed Under: Everything

Primary Sidebar

The work of the information officer [should be] regarded as the natural dynamic extension of that of the librarian.

Douglas John Foskett

Subscribe via Email

Subscribe via email and you will receive my latest blog posts in your inbox. No ads or spam, just the same great content you find on my site!
 New posts (daily)
 Where's Stephen? (weekly)

Download My Book


Download my free e-book:
Essential Enterprise Storage Concepts!

Recent Posts

How To Install ZeroTier on TrueNAS 12

February 3, 2022

Scam Alert: Fake DMCA Takedown for Link Insertion

January 24, 2022

How To Connect Everything From Everywhere with ZeroTier

January 14, 2022

Electric Car Over the Internet: My Experience Buying From Vroom

November 28, 2020

Powering Rabbits: The Mean Well LRS-350-12 Power Supply

October 18, 2020

Tortoise or Hare? Nvidia Jetson TK1

September 22, 2020

Running Rabbits: More About My Cloud NUCs

September 21, 2020

Introducing Rabbit: I Bought a Cloud!

September 10, 2020

Remove ROM To Use LSI SAS Cards in HPE Servers

August 23, 2020

Test Your Wi-Fi with iPerf for iOS

July 9, 2020

Symbolic Links

    Featured Posts

    On the Death of Innovation, or “These Kids These Days!”

    May 21, 2012

    How To Sync Your iPad With Your Exchange Server

    April 3, 2010

    Cisco’s Trojan Horse

    September 15, 2014

    Regarding My Symbolic Links and Good Reads

    April 16, 2015

    The iPhone Revolution 10 Years Later

    January 9, 2017

    The Prime Directive of Storage: Do Not Lose Data

    December 12, 2014

    Aerobie AeroPress Review: The Hacker Coffee Maker

    February 7, 2011

    Why Big Disk Drives Require Data Integrity Checking

    December 19, 2014

    Instapaper for iPad and iPhone Enhances My Web World

    June 1, 2010

    Are You a Hypervisor Hugger or a Storage Stalwart?

    November 14, 2011

    Footer

    Legalese

    Copyright © 2022 · Log in