[ale] Backup large files to span DVDs

[DJ-Pfulio]

Below won't help Alex.  Some environments are locked down and we have to live
with it. I wish more were - like chemical plants, power plants, other control
centers. I understand completely, having deployed one of those.

Getting **any** new code introduced just isn't worth the effort
post-systems-deployment. Places like that are in "the devil we know" mode, which
is completely understandable. Introducing **anything new** into these
environments can break things ... or worse! There are extremely good reasons for
this.

Don't know if parchive is the same code as par2, which I've been using for over
a decade now.

par2 has saved some of my data a few times. Some of the optical media is over a
decade old and only losing a few bits here and there.  Call it "nice to have"
data, not mission critical.
http://blog.jdpfu.com/2011/06/12/optical-data-recovery-technique-with-ddrescue-and-par2
 explains a use to recover almost lost data with assurance that it is the same
as what was archived.  It has a trivial par2 creation script.


On 10/28/2015 02:37 PM, Alex Carver wrote:
> On 2015-10-28 11:24, James Sumners wrote:
>> On Wed, Oct 28, 2015 at 2:07 PM, Alex Carver <agcarver+ale at acarver.net>
>> wrote:
>>
>>> Parchive is not currently on the approved list of utilities.  I can only
>>> use very well known utilities and methods that have a high degree of
>>> longevity in terms of support or understanding.  Things like tar and cat
>>> are very well understood, have been around for decades and are not
>>> likely to go anywhere for a long time.  Parchive hasn't been around as
>>> long and the specification and implementation is still changing.
>>>
>>
>> I'm not clear on your understanding of how Parchive works and what it is
>> for. It's merely for verifying the integrity of data, and repairing said
>> data if there is corruption. It is not an archive file format ala tar, zip,
>> et alii.
>>
>> As for longevity, Parchive is nothing more than an application of
>> Reed-Solomon coding. The algorithm isn't new, and it is used pretty much
>> everywhere[1].
>>
>> [1] -- https://en.wikipedia.org/wiki/Reed–Solomon_error_correction
> 
> 
> I understand that it's not a file format itself but it does require an
> additional utility to implement the method (the parchive client) and
> that's what I'm not allowed to use.  Generating the parity files would
> just be a waste of time in this case because I would not be able to get
> the utility approved.  The current approved method for corruption
> mitigation is multiple media types and duplicate copies (e.g. a magnetic
> copy, an optical copy, a hard copy for things that can be printed, etc.)
> 
> I'll certainly consider it for my personal data storage because it looks
> like a good thing to have, but I just can't do it at work.  This is why
> there are ten hard drives, many spindles of disc blanks, and lots of
> binders at my desk.
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