Hard Disk Drive Myths Debunked!

Discussion in 'Reviews & Articles' started by Adrian Wong, Mar 16, 2004.

  1. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 4.4

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    In this update, we added three new myths :

    We now have 43 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 4.4
     
  2. cypherpunks

    cypherpunks Newbie

    Actually Myth #16 is true, on IBM/Hitachi drives

    In a limited sort of way. Sending the IBM-specific "FORMAT UNIT" command will zero out SMART counter #5, "Reallocated Sector Count" and improve the performance of a drive with bad sectors.

    But no, it doesn't fix them.

    This is because there are two ways of handling bad sectors, known as "slipping" and "sparing".

    During initial block allocation, a drive with bad sectors is assigned sector numbers [1][2][3][4][bad][bad][5][6][7]...[100][spare][spare][spare]. Bad (and spare) sectors are simply skipped over in the sector numbering, so that sequential sector numbers are stored sequentially on disk. the gap might just be a bit larger than you expect. This is called "slipping" the sector numbers, because the logical sector numbers just "fall behind" the physical sector numbers slightly.

    If sector 6 goes bad, it will be reassigned to the first spare sector, so you'll get[1][2][3][4][bad][bad][5][BAD][7]...[100][6][spare][spare]. Now, sequential sector numbers are no longer stored sequentially. Instead, reading sectors 5-6-7 results in two seeks!

    This is called "sparing" the sector, replacing it with a spare. But without moving the data in between, the spare has to be out of sequence. Essentially, you've fragmented your drive.

    IBM (and only IBM, as far as I know), which is now Hitachi Global Storage Technologies, documented a vector-specific command which will reassign the sector numbers, fixing the fragmentation. The result is [1][2][3][4][bad][bad][5][bad][6]...[99][100][spare][spare]. The bad sectors are still there, but they don't hurt performance as much.

    It's particularly useful on RAID setups, where a hiccup in reading any drive results in a hiccup reading the whole RAID.

    See, for example, the Travelstar 7K100 manual (google for "7K100_SATA_spv2.1.pdf"; I can't post links yet), page 84 (page 96 of the PDF).
     
    Last edited: Jul 28, 2011
  3. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Thanks for the heads-up, cypherpunks! Will take a look at the 7K100 manual! :thumb:
     
  4. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 4.5

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    In this update, we added two new myths :

    We also updated Myth #16 on the reformatting of hard disk drives to fix bad sectors.

    We now have 45 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 4.5
     
  5. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 4.6

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    In this update, we updated two myths :

    We now have 45 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 4.6
     
  6. lee_what2004

    lee_what2004 Just Started

    http://www.symbianize.com/showthread.php?t=55482

    Any comment about it ?
     
  7. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Not possible AFAIK. Bearings don't get "locked" into a particular orientation no matter how long you put them in one particular orientation.

    But thanks for the link. This is a good myth to add to the guide. :thumb:
     
  8. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 4.7

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    In this update, we added three new myths :

    We now have 48 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 4.7
     
  9. lee_what2004

    lee_what2004 Just Started

  10. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Really? It works for me. :think:

    Can you try refreshing the page?
     
  11. lee_what2004

    lee_what2004 Just Started

    Now its working :thumb: . Before that its error loading article.
     
  12. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hmm.. I think you may have loaded the article while I was uploading an update. :D
     
  13. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 4.8

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    In this update, we added two new myths :

    We now have 50 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 4.8
     
  14. belikethat

    belikethat Just Started

    2 thumbs up, that two good topics
     
  15. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Thanks! :)
     
  16. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 4.9

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    Here are the changes in this update :

    We now have 52 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 4.9
     
  17. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 5.0

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    Here are the changes in this update :

    We now have 55 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 5.0
     
  18. mitchu

    mitchu Newbie

    Inside a hard drive assembly is a vacuum. Probably the most common delusion. I really don’t understand why people think this way, it’s not possible in principle, because magnetic heads float above the disk surface due to the air flow generated by revolving platters. So if there is no air, a hard drive will not be able to work according to the laws of physics. In reality, a hard drive assembly contains an ordinary, filter purified air with the same pressure asoutside the assembly, more on <http://www.dataretrieval.com/blog/hard-disk-drives/debunking-hdd-myths.html>
     
    Last edited: May 9, 2013
  19. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hmm... We didn't add that yet? Thanks for the heads-up! Will add it to the next update! :thumb:
     
  20. Adrian Wong

    Adrian Wong Da Boss Staff Member

    Hard Disk Drive Myths Debunked! Rev. 5.1

    This guide was written in response to the numerous fallacies about the hard disk drive that are still being propagated in many forum discussions.

    As you read through this guide, you may think that some of these myths may have been made up. We wished that was true. We collected these myths from various discussions we heard or read over time.

    So, let's get down to basics and examine some of these common fallacies or myths and debunk them!

    Here are the changes in this update :

    We now have 57 HDD myths in this article!


    [​IMG]

    Link : Hard Disk Drive Myths Debunked! Rev. 5.1
     

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