[Tig] Archiving (was Re: Holographic Drive at NAB)

Jim Houston jdhouston at earthlink.net
Tue Apr 22 05:38:24 BST 2008


On Apr 21, 2008, at 2:38 PM, Ted Langdell wrote:
>
> ... advocates transferring to mirrored hard drives and shelving
> them.

This is a poor idea.  As it turns out, hard drives have significant  
problems
from an archival standpoint that make tape a better and safer medium.
Among the issues are that hard drives spin on a bearing that is coated
with a volatile oil.  Whether you run the drive or not, this oil  
degrades
over time and can cause stickion.   Most drives are designed
with a 3-5 year lifetime and the failure curve at the beginning of their
life and within months of the end of the design life are very high.
The built-in heads and unsealed nature of all drives (so that the
head floats over the disk surface from airflow) makes head crashes
much more likely over time.  While it is true that drive manufacturers
could manufacture safe 25-year drives, there is no economic incentive
to do so because of how fast the capacity changes.  If you store it  
properly
and can keep the tape machine running, tape lasts much longer than
hard drives.

(and as far as the Holographic drives go,  I heard a detailed talk on  
all
of the error-correction mechanisms that had to be designed into
the InPhase drives.  While it may prove out to have solid engineering,
anything that needs as many layers and methods of error correction
as this drive does is a bit suspect from an archival standpoint.
With holographic storage, if you lose alignment of the reference beam
you lose all your data.  So there are many methods at play on the
drive to correct for tracking and alignment errors. Much more so than
on a typical hard drive.  It remains to be seen if the system will be  
reliable
over time.)

Jim H.
Postworks L.A.




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