[ale] read after write verify?, data scrubbing procedures

[Ron Frazier (ALE)]

Hi Erik,

Thanks.  I've heard about this Google study but haven't read through it.  I'll try to do that.  Should be interesting.

Sincerely,

Ron


Erik Mathis <erik at mathists.com> wrote:

>Ron, this might be of some interest to you from our overlords at google
>
>http://tinyurl.com/95xdrwv
>
>On 10/25/2012 04:43 PM, Ron Frazier (ALE) wrote:
>> Hi all,
>>
>> In another thread, I mentioned that I do a manual data scrubbing
>procedure on my hard drives which involves reading inverting writing
>reading inverting writing all sectors on the hard drive periodically
>with Spinrite.  As an alternative, I use the Linux badblocks non
>destructive read write mode.  This process is certainly effective in
>reverifying the integrity of the drive barring any mechanical problems
>or controller problems.  As also mentioned in another thread, once some
>drives develop bad sectors, and based partly on advice here, I replace
>them.
>>
>> I basically want to have as much evidence as I can that the drive is
>reliable, periodically, still understanding that spontaneous or semi
>spontaneous failures are possible.
>>
>> I am considering methods of reducing the maintenance procedures while
>still maintaining high confidence in the drives.  Mike T mentioned some
>automation and raid procedures that I may be able to implement on some
>machines at a future date.  In the mean time, I'm considering altering
>my procedures without giving up too much functionality.
>>
>> My first question is, does a HDD do a read after write verify by
>default?  So, if the application or OS sends a command to write a
>sector, will a verify operation automatically be done after the write
>process, and, if the write failed, will the data be automatically
>relocated to a spare sector?  I'm assuming that this is the case, but
>would like to verify that.
>>
>> Assuming the read after write verify happens, then, if I write data
>to every sector of a drive during a backup operation, as I mentioned in
>the clonezilla thread, then, effectively, I have written and read every
>sector on the target drive.  Perhaps, then, a successful backup
>operation can take the place of my data scrubbing activity on the
>target drive.
>>
>> Then, there is the question of the data scrubbing on the source
>drive.  In this case, once I've completed a backup, I will have read
>each sector on the source drive.  Assuming there are no read errors, 
>(If there were, I have to get out the big guns.)  then, this has
>accomplished 1/2 of what my scrubbing does, the read half.
>>
>> So, the question arises as to what about the write test part of my
>scrubbing operation for the source drive, which didn't get done. 
>Normally, my scrubbing operation would have written to each sector.  If
>the drive automatically detects write problems when a write is
>attempted, perhaps the write scrubbing operation is not necessary, or
>is less necessary.
>>
>> Hope this makes any sense whatsoever.  Any opinions?
>>
>> Thanks in advance.
>>
>> Sincerely,
>>
>> Ron
>>
>>
>>
>> --
>>
>> Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9
>Mail.
>> Please excuse my potential brevity.
>>
>> (To whom it may concern.  My email address has changed.  Replying to
>former
>> messages prior to 03/31/12 with my personal address will go to the
>wrong
>> address.  Please send all personal correspondence to the new
>address.)
>>
>> (PS - If you email me and don't get a quick response, you might want
>to
>> call on the phone.  I get about 300 emails per day from alternate
>energy
>> mailing lists and such.  I don't always see new email messages very
>quickly.)
>>
>> Ron Frazier
>> 770-205-9422 (O)   Leave a message.
>> linuxdude AT techstarship.com
>>
>>
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--

Sent from my Android Acer A500 tablet with bluetooth keyboard and K-9 Mail.
Please excuse my potential brevity.

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new email messages very quickly.)

Ron Frazier
770-205-9422 (O)   Leave a message.
linuxdude AT techstarship.com