Re: [ARSCLIST] Longevity of data tape?--

[Jeffrey Kane <jeffkane@xxxxxxxxxxxxxxx>]

I specifically was referring to DAT. As an amateur, I only have very limited
experience with ADAT and none with DTRS or DASH. I have personal experience
with DAT, LTO, AIT and DLT used for data archival. The principle applies to
all of the above unless my understanding is mistaken.

As an example; say a track is archived to both DASH and LTO. After six
years, both are pulled out to restore the material (remastering, what have
you). For whatever reason (environmental problems, magnetic field exposure,
handling damage, oxide shedding, etc) both tapes are damaged and 5 feet of
tape is rendered useless. In the case of the DASH reel, only the material
contained in that segment of tape will be lost, the rest can be recovered.
In the case of the LTO tape, whatever file that section of tape contained is
lost in it's entirety. Were the LTO tape to contain separate files
representing the tracks on the DASH master, one entire track would be lost
as that file written to the area now damaged cannot easily be reconstructed
(or not at all if the material were compressed, encrypted, or both). Were
the LTO to contain one large file containing the separate tracks (say a Pro
Tools Macintosh Stuffit archive, necessary to preserve resource forks), the
entire project would be lost.

Obviously exceptions exist. I maintain that data archiving methods offer
greater data resilience; digital audio storage methods suffer less data loss
when damage results in unrecoverable errors.



-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx] On Behalf Of John Spencer
Sent: Thursday, June 09, 2005 8:08 PM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] Longevity of data tape?--

Jeff,

I was curious if you could elaborate further on your initial post:

  "With digital audio tape the error only affects that portion of the
recording"

Which format of digital audio tape are you referring to?  R-DAT/
DASH/ PD?

Were you stating that you prefer digital audio tape formats to
Enterprise-class data storage tapes?

John
John Spencer
www.bridgemediasolutions.com


On Jun 9, 2005, at 4:52 PM, Jeffrey Kane wrote:

> I don't believe I explained myself properly. Most backup
> applications will
> skip a bad block (or even several blocks) of data and continue the
> restore.
> What I describe arises when the corruption exceeds the ability of the
> software to recover from errors. In that case, an entire file (or
> several if
> not the whole tape depending on the location of the error) will be
> rendered
> unrecoverable. The validation of the archive/backup at the time
> only ensures
> the initial process succeded. The problematic variable is between
> archival
> and retrieval. With digital audio recordings, such errors will only
> render
> that portion of the recording unrecoverable.
>
> As for error correction, that is a function of the format (AIT/LTO/
> DLT/etc)
> and software used for backup/archival. On 'trusting' a datatape to be
> readable 25-30 years from now; I completely agree. That is the
> figure I
> recall being used when discussing longevity. In my case, I re-archive
> critical material every three years. Data on tape IMO is far too
> susceptible
> to corruption to be relied upon for a longer timeframe than that.
>
> Jeff
>
>
>> -----Original Message-----
>> From: Association for Recorded Sound Discussion List
>> [mailto:ARSCLIST@xxxxxxx] On Behalf Of John Spencer
>> Sent: Thursday, June 09, 2005 2:47 PM
>> To: ARSCLIST@xxxxxxxxxxxx
>> Subject: Re: [ARSCLIST] Longevity of data tape?--
>>
>> This is an incorrect statement.  There are various backup
>> applications that will skip a bad block of data and continue
>> the restore process, as well as applications that will report
>> on the quality of the data archive as it is being written.
>> Error correction is not a function of the data storage tape itself.
>>
>> And I would never trust a data storage tape to be readable
>> 25-30 years from now.
>>
>> John
>> John Spencer
>> www.bridgemediasolutions.com
>>
>>
>> On Jun 9, 2005, at 2:36 PM, Jeffrey Kane wrote:
>>
>>
>>> I've seen the figure 25-30 years bandied about for data tape. Data
>>> backups are a double edge sword. They have better error
>>>
>> correction so
>>
>>> the data is more resilient. However, if there's an
>>>
>> unrecoverable error
>>
>>> it renders ALL data for that particular file (and if it's in the
>>> directory area, all data on the tape) unrecoverable. With digital
>>> audio tape the error only affects that portion of the recording.
>>>
>>>
>>
>>
>
>