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Re: [ARSCLIST] Testing DVDs
Hi John,
I use mainly LTO for my clients requirements, when it comes to tape... with
great success so far...
Basically... for any archive that has to work within a budget, any
physically checking of media can be very expensive if one has to invest in
hardware to accomplish the task... or hire people... I wouldn't suggest
getting the guy from the "corner of the street".
As an example... we consider ALL physical media as a future problem. When we
archive for LTO we only use half the life expectancy of the drive, in the
hope that future disaster recovery will benefit from us storing the original
drive that generated the tape with the tapes... this is due to head
alignment etc...
Practically, we are located 250 ft underground... and have mirror sites
around the US for physical separation.
I have nothing against physical based storage, but my point is that anything
that is based on physical assets will by default deteriorate over time...
I hope this clarifies my statements...
Claus.
Claus Trelby
Managing Engineer/Partner
XEPA Digital
1137 Branchton Road, 19-N-3
Boyers, PA 16020-0137
www.xepadigital.com
ctrelby@xxxxxxxxxxxxxxx
P:724-794-3686
F:724-794-3292
C:805-490-1730
-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of John Spencer
Sent: Thursday, June 02, 2005 11:22 PM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] Testing DVDs
Could you please elaborate on your statement:
"Even if you can check a disc type media physically I think it will
be hard to check something like
Exabyte or LTO on a regular basis without tearing the media apart..."
Disregarding Exabyte drives and tapes, LTO is the largest selling
data storage tape drive in the Enterprise IT environment,
and they seem to be pretty happy with it. Most of the media vendors
do 1,000,000+ pass testing and are eager
to share the results (Fuji is very good about sharing their
information). I agree that RAID is a great option, but
near-line solutions should be looked at as a potential part of the
digital archive process.
Geographical separation comes to mind in this instance.
John Spencer
www.bridgemediasolutions.com
On Jun 2, 2005, at 8:59 PM, Claus Trelby wrote:
> Hi Peter (all),
>
> Without going into physical indicators and complexities for disc media
> failure, I would just like to add a little suggestion to all of
> this...
>
> We want to preserve the data, right? A minimum of two different
> types of
> media for storage plus a checksum file such as MD5 placed in the
> middle
> storage area of the media (tape or disc) is our default... we then
> spot
> check all media periodically (especially edge content or all
> content), and
> any deviation from the checksum results in alerts... Even if you
> can check a
> disc type media physically I think it will be hard to check
> something like
> Exabyte or LTO on a regular basis without tearing the media apart...
>
> Just a suggestion.... I've personally stopped paying attention to
> accelerated media testing... I find it useless... history always
> proves it
> wrong...
>
> I believe spinning/exercised RAID disc (HD) storage is the only way
> to go...
> still very expensive, but a couple of the companies I am consulting
> for are
> getting in the right ball park... less than $4 per GB (22TB
> minimum)...
>
> Claus.
>
> Claus Trelby
> Managing Engineer/Partner
>
> XEPA Digital
> 1137 Branchton Road, 19-N-3
> Boyers, PA 16020-0137
> www.xepadigital.com
> ctrelby@xxxxxxxxxxxxxxx
> P:724-794-3686
> F:724-794-3292
> C:805-490-1730
>
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx]On Behalf Of Peter@xxxxxxxxxxxxx
> Sent: Thursday, June 02, 2005 7:43 PM
> To: ARSCLIST@xxxxxxxxxxxx
> Subject: Re: [ARSCLIST] Testing DVDs
>
>
> I will be attending the AES/ISO meeting of the Technical Commission
> on Tape
> and Disc preservation this coming week. We have been discussing
> ways of
> testing DVD's and it is a subject that is part of next week's
> agenda. So
> far, it is unfortunately true that the testing methods developed and
> recommended are somewhat too cumbersome and time-consuming to be
> widely
> practical. If we review any documents that offer reasonable
> alternatives, I
> will report such to the list.
>
> One of the primary failure mechanisms that needs more testing is
> delamination. In my opinion, from review of the available data,
> there is
> not enough reliable information on the stability and reactive
> properties of
> the glue used to bond the layers together. If someone has a good,
> quick way
> to test the glue stability, I would be pleased to pass it on to the
> Commission.
>
> One of the problems encountered (again, in my opinion) is that
> testing for
> new mediums tends to mimic the tests for previous mediums.
> Accelerated
> aging tests for recordable sound media were initially developed to
> try and
> test binder hydrolysis. Discs are a very different animal than tape.
> Polycarbonate disc surfaces do not hydrolyze like polyester binder
> in tape.
> On the other hand, reflective mediums in Discs can oxidize while
> ferric
> oxide recording pigments in older tape don't. Again, the binder
> mechanism
> on tape is integral to the entire recording layer while Discs are
> actually
> held together with an added layer of glue.
>
> It is quite possible that we need to seriously re-think the testing
> parameters and methods for Discs. Again, if anyone has some
> suggestions, I
> would be glad to pass them along.
>
>
> Peter Brothers
> President
> SPECS BROS., LLC
> (201) 440-6589
> www.specsbros.com
>
> Restoration and Disaster Recovery Service Since 1983
>
>
>> -----Original Message-----
>> From: Association for Recorded Sound Discussion List
>> [mailto:ARSCLIST@xxxxxxx]On Behalf Of seva
>> Sent: Thursday, June 02, 2005 9:38 AM
>> To: ARSCLIST@xxxxxxxxxxxx
>> Subject: Re: [ARSCLIST] Testing DVDs
>>
>>
>> i think that querying Mitsui itself would yield more information.
>> they
>> have a sterling reputation and i'm sure would have no intention to
>> launch the gold DVDs without serious advanced aging tests of their
>> own...
>>
>>
>> David Lewiston wrote:
>>
>>
>>> So there are plenty of brilliant comments, but no practical
>>>
>> suggestions for
>>
>>> doing a quick and dirty test?
>>>
>>> Salutations, David L
>>>
>>>
>>> ----- Original Message -----
>>> From: "Nigel Champion (ARTS ANT)" <n.champion@xxxxxxxxxxxxxx>
>>> To: "David Lewiston" <david.lewiston@xxxxxxxxxxx>
>>> Sent: June 01, 2005 4:35 PM
>>> Subject: RE: [ARSCLIST] Gold DVD-Rs
>>>
>>>
>>> Then you need to repeatedly insert and remove the DVD-R from its'
>>> case.
>>> This is to find how long it takes to separate the two polycarbonate
>>> layers of the DVD!
>>>
>>> Regards
>>> Nigel
>>>
>>>
>>>
>>>
>>
>> --
>> salutations,
>> seva
>>
>> www.soundcurrent.com
>> || | | | | | | | |
>>
>> Things are not what they seem to be; nor are they otherwise.
>> -- Lankavatara Sutra
>>
>>
>>
>
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