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Re: big drives

From Don Y <blockedofcourse@foo.invalid>
Newsgroups sci.electronics.design
Subject Re: big drives
Date 2017-03-24 16:56 -0700
Organization A noiseless patient Spider
Message-ID <ob4bih$sg$1@dont-email.me> (permalink)
References (3 earlier) <hq06dcd2kq40eh0tpg4s8pee977cnr48h4@4ax.com> <oav0p0$m1m$2@dont-email.me> <6o26dct4ihbqtg8l94crijgnou7hmapao0@4ax.com> <oavpbi$ac6$1@dont-email.me> <mtuadcd89esq21qacd2kovqebckmcbchib@4ax.com>

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On 3/24/2017 1:06 PM, John Larkin wrote:
> On Wed, 22 Mar 2017 23:21:15 -0700, Don Y
> <blockedofcourse@foo.invalid> wrote:
>
>> On 3/22/2017 4:45 PM, John Larkin wrote:
>>> On Wed, 22 Mar 2017 16:21:45 -0700, Don Y
>>> <blockedofcourse@foo.invalid> wrote:
>>>
>>>> On 3/22/2017 4:07 PM, John Larkin wrote:
>>>>> On Wed, 22 Mar 2017 16:37:02 -0500, Jon Elson <jmelson@wustl.edu>
>>>>> wrote:
>>>>>
>>>>>> tabbypurr@gmail.com wrote:
>>>>>>
>>>>>>> On Tuesday, 21 March 2017 17:21:23 UTC, John Larkin  wrote:
>>>>>>>> I just happened to open my recycle bin and there was 42 Gbytes of
>>>>>>>> junk.
>>>>>>>>
>>>>>>>> I remember 256 Kbyte hard drives. A PC with a 10M drive was top-end.
>>>>>>>>
>>>>>>>> There's no point in reducing jpeg sizes, or even deleting stuff, any
>>>>>>>> more. I could never take enough pics, or create enough docs, to keep
>>>>>>>> up with the progress in hard drives. I suppose some people could
>>>>>>>> collect a large number of HD movies and use a terabyte somehow.
>>>>>>>>
>>>>>>>> It's impossible to crack one-time-pad encryption. Giant hard drives
>>>>>>>> and memory sticks make OTP files easy to physically hand off to
>>>>>>>> correspondents.
>>>>>>>
>>>>>>> I estimated the payback of deleting data some time last year. It came in
>>>>>>> at something like a penny or 2 an hour.
>>>>>> Well, the problem is I want physical, off-line backup of important stuff
>>>>>> (that's what I've created, not the OS, utilities, etc.) preferably located
>>>>>> in a couple places.  So, getting rid of excess junk and redundant on-line
>>>>>> backups makes some sense, in thaty it makes those CDs, then DVDs, now Blu-
>>>>>> Ray backups fit on available media.
>>>>>>
>>>>>> jon
>>>>>
>>>>> We back up to USB terabyte hard drives and use them as write-once
>>>>> media.
>>>>
>>>> And what ongoing *policy* do you have to verify their contents are still
>>>> accessible (i.e., that the disk hasn't developed a flaw) *and* intact?
>>>
>>> Massive redundancy. If 90% of the off-site drives die, we'll still be
>>> OK.
>>
>> I've a friend who thought copying all of his ROM images, etc. onto his
>> PC and routinely backing up his PC was a great way to ensure he could
>> always recreate ROMs.
>>
>> Some years later, he was patching a ROM and botched the job.  No way to
>> "click undo" and recreate the original ROM.  *But*, hey, the image of
>> the ROM is present on his PC, right?
>>
>> Imagine his dismay to discover that the image on the PC couldn't
>> possibly correlate with even the *bulk* of the botched ROM that he
>> had before him!  (locations that were "burned to 0" in the image but
>> NOT burned in the actual ROM)
>>
>> Obviously, at some point in the past, he had copied the file incorrectly
>> (either by some manual operation on his part *or* some screwup in the
>> backup/restore program).  So, all of those backups over the years had
>> successfully backed up a defective copy of the ROM image!
>
> That's the reason to often use write-once backup media, take then off
> site, store them in ziplox bags in a cool dry place. If a file gets
> corrupted, some old back will have the original version. It doesn't
> make sense to resuse or ever write over backup drives.

That only works if you can find a backup copy that is intact.  And,
have some way of proving (to yourself) that it is intact.

In my approach, that proof comes in the form of preserving the copy and
its hash (in separate places).

In my friend's case, having a ROM and an image that can't possibly correspond
with that ROM (i.e., proof that it is corrupt).

I have everything that I've ever created in electronic form (plus lots of
things that I've converted *to* electronic forms) in my career (and a bit
before).  But, I don't have every *backup* instance of those things -- just
the "originals" and copies thereof.

I make a daily backup of my "development database" (about 20GB) on alternating
drives, replacing the oldest version that exists on the drive (so, I can go
back a few months to see what changed).  But, only keep checkpointed snapshots
very infrequently -- in the VCS (changes since the most recent snapshot aren't
formally documented; they exist solely to let me move back and forth in time
*informally* to see what I did "the day before yesterday")

I contend that the flaw in most backup strategies is the lack of positive
confirmation that the "copies" are true representations of the contents at
the time they were created (i.e., bytewise compare to the originals), still
intact (haven't been altered, media hasn't degraded, etc.) and recoverable
(i.e., you know HOW to get the copy back despite LIKELY being in a state
of near panic when that need arises!)

Had my friend followed a similar approach as mine, he'd have known the instant
the ROM image(s) had been corrupted and would/could have taken corrective
action at that time.  Instead, he kept backing up "bad data" (10 copies of bad
data don't compensate for one *good* datum!)

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Thread

big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-21 10:21 -0700
  Re: big drives bitrex <bitrex@de.lete.earthlink.net> - 2017-03-21 13:47 -0400
    Re: big drives George Herold <gherold@teachspin.com> - 2017-03-21 12:42 -0700
      Re: big drives dagmargoodboat@yahoo.com - 2017-03-21 12:55 -0700
        Re: big drives George Herold <gherold@teachspin.com> - 2017-03-21 13:37 -0700
          Re: big drives bill.sloman@ieee.org - 2017-03-21 21:51 -0700
            Re: big drives George Herold <gherold@teachspin.com> - 2017-03-22 07:26 -0700
  Re: big drives Winfield Hill <hill@rowland.harvard.edu> - 2017-03-22 03:38 -0700
    Re: big drives Don Kuenz <g@crcomp.net> - 2017-03-22 14:23 +0000
      Re: big drives David Brown <david.brown@hesbynett.no> - 2017-03-22 16:43 +0100
        Re: big drives Don Kuenz <g@crcomp.net> - 2017-03-22 18:35 +0000
          Re: big drives David Brown <david.brown@hesbynett.no> - 2017-03-23 10:24 +0100
            Re: big drives Don Kuenz <g@crcomp.net> - 2017-03-23 16:11 +0000
              Re: big drives krw@notreal.com - 2017-03-23 13:05 -0400
                Re: big drives Don Kuenz <g@crcomp.net> - 2017-03-23 17:39 +0000
                Re: big drives krw@notreal.com - 2017-03-23 21:05 -0400
                Re: big drives Don Kuenz <g@crcomp.net> - 2017-03-24 03:01 +0000
                Re: big drives krw@notreal.com - 2017-03-23 23:09 -0400
                Re: big drives Don Kuenz <g@crcomp.net> - 2017-03-24 04:15 +0000
                Re: big drives krw@notreal.com - 2017-03-24 22:34 -0400
      Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 12:25 -0700
        Re: big drives dplatt@coop.radagast.org (Dave Platt) - 2017-03-22 13:57 -0700
          Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 16:03 -0700
        Re: big drives krw@notreal.com - 2017-03-22 20:29 -0400
  Re: big drives tabbypurr@gmail.com - 2017-03-22 04:36 -0700
    Re: big drives Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-03-22 08:57 -0400
      Re: big drives Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-22 11:59 -0400
        Re: big drives krw@notreal.com - 2017-03-22 13:23 -0400
          Re: big drives Jon Elson <jmelson@wustl.edu> - 2017-03-22 16:38 -0500
            Re: big drives krw@notreal.com - 2017-03-22 20:31 -0400
            Re: big drives gray_wolf <g_wolf@nospam.com> - 2017-03-23 20:59 -0500
            Re: big drives gray_wolf <g_wolf@nospam.com> - 2017-03-23 21:00 -0500
        Re: big drives Robert Baer <robertbaer@localnet.com> - 2017-03-23 22:21 -0800
    Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-22 07:51 -0700
      Re: big drives krw@notreal.com - 2017-03-22 13:23 -0400
      Re: big drives Robert Baer <robertbaer@localnet.com> - 2017-03-23 22:19 -0800
      Re: big drives tabbypurr@gmail.com - 2017-03-24 04:26 -0700
        Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 08:38 -0700
    Re: big drives Jon Elson <jmelson@wustl.edu> - 2017-03-22 16:37 -0500
      Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-22 16:07 -0700
        Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 16:21 -0700
          Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-22 16:45 -0700
            Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 23:21 -0700
              Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 13:06 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 16:56 -0700
                Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 17:35 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 21:47 -0700
      Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 16:19 -0700
        Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-22 16:50 -0700
          Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 17:58 -0700
            Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-22 21:00 -0700
              Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-22 22:50 -0700
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-23 08:27 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-23 12:25 -0700
      Re: big drives tabbypurr@gmail.com - 2017-03-24 04:31 -0700
        Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 06:38 -0700
          Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 08:41 -0700
            Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 11:38 -0700
              Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 13:55 -0700
              Re: big drives tabbypurr@gmail.com - 2017-03-24 17:14 -0700
                Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 17:41 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 18:00 -0700
  Re: big drives Joerg <news@analogconsultants.com> - 2017-03-23 09:35 -0700
  Re: big drives "Michael A. Terrell" <mike.terrell@earthlink.net> - 2017-03-23 18:38 -0400
    Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-23 16:18 -0700
      Re: big drives Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-23 18:29 -0400
        Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-23 18:38 -0700
          Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-23 18:54 -0700
            Re: big drives pcdhobbs@gmail.com - 2017-03-23 19:16 -0700
              Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-23 19:28 -0700
                Re: big drives pcdhobbs@gmail.com - 2017-03-23 19:55 -0700
                Re: big drives krw@notreal.com - 2017-03-23 23:04 -0400
                Re: big drives pcdhobbs@gmail.com - 2017-03-23 22:00 -0700
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 08:46 -0700
                Re: big drives krw@notreal.com - 2017-03-24 22:38 -0400
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-23 22:22 -0700
                Re: big drives pcdhobbs@gmail.com - 2017-03-23 23:08 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 00:21 -0700
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 09:00 -0700
                Re: big drives David Brown <david.brown@hesbynett.no> - 2017-03-24 17:14 +0100
                Re: big drives tabbypurr@gmail.com - 2017-03-24 09:19 -0700
                Re: big drives David Brown <david.brown@hesbynett.no> - 2017-03-24 17:47 +0100
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 12:01 -0700
                Re: big drives Jasen Betts <jasen@xnet.co.nz> - 2017-03-24 20:30 +0000
                Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 14:06 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 11:55 -0700
                Re: big drives "Michael A. Terrell" <mike.terrell@earthlink.net> - 2017-03-25 04:00 -0400
                Re: big drives upsidedown@downunder.com - 2017-03-24 22:18 +0200
                Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 14:15 -0700
                Re: big drives Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-25 13:21 +0200
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-25 07:54 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-25 10:53 -0700
                Re: big drives upsidedown@downunder.com - 2017-03-25 23:11 +0200
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-25 15:14 -0700
                Re: big drives upsidedown@downunder.com - 2017-03-26 12:18 +0300
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-26 03:33 -0700
                Re: big drives Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-03-26 16:36 -0400
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-26 14:13 -0700
                Re: big drives Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-25 21:04 +0200
                Re: big drives pcdhobbs@gmail.com - 2017-03-24 19:03 -0700
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 08:53 -0700
                Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 12:12 -0700
                Re: big drives John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-03-24 14:20 -0700
                Re: big drives krw@notreal.com - 2017-03-24 22:43 -0400
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 20:10 -0700
                Re: big drives krw@notreal.com - 2017-03-24 23:23 -0400
                Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-24 22:25 -0700
                Re: big drives Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-03-25 13:23 +0200
        Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-23 19:36 -0700
      Re: big drives upsidedown@downunder.com - 2017-03-24 10:14 +0200
        Re: big drives Don Y <blockedofcourse@foo.invalid> - 2017-03-24 01:31 -0700
    Re: big drives John Larkin <jjlarkin@highlandtechnology.com> - 2017-03-23 16:21 -0700
      Re: big drives "Michael A. Terrell" <mike.terrell@earthlink.net> - 2017-03-24 08:54 -0400

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