Le vendredi 08 Septembre 2006 04:35, Chuck Norcutt a écrit :
> If you're really going to write to CD's and DVD's you shouldn't be using
> anything other than these or an equivalent if you can find it.
> <http://store.mam-a-store.com/standard---archive-gold.html>
> One other option is the Kodak Gold CD which is now back in production
> after being amongst the missing for a number of years.
> This store sells Kodak <http://www.datamediastore.com/kodak.html> and
> MAM-A <http://www.datamediastore.com/mamamitsui.html>
I certainly wouldn't trust a CD or DVD for important backups, however good
reviews they get. On top of the reasons I wouldn't do it, consumer grade
burners have a tendency to be more and more loosy at writing correctly, and
rely more and more on the electronic to save their day with accurate CRC.
This is really bad because unless you hook the reader on an analysis
equipement to show raw read errors, you have no means to know how bad your
disk was written in the first place, the side effect being that on weak
bytes, sometimes a single misread bit can become a complete showstopper for
the whole medium. Optical disk were never, ever, intended to store datas.
This is just a terrible hack, only making sense for economical reasons. But
as always, one get what has been paid for - not much. I know someone geared
to do such analysis who did test some writers and was amazed in the end that
he could actually read the disks with so many errors on them. And he
analysed *freshly burned* disks. And just to scare anyone here : hard disks
are as bad as CDs ; but the actual structure of a hard disk (in head /
track / sector) does not make this issue as sensitive as it is on a single
medium like a CDs, because a single read failure does not prevent the reading
of good parts.
That's no wonder if pro backups still rely on - basically - magnetic tapes
since... forever.
> But I think several hard drives are a more attractive option. I saw a
> 250GB (I think) drive the other day going for $59 with rebate. You can
> buy a couple of these for the price of 100 MAM-A gold CD's. A lot
> faster and less hasssle too.
Keeping datas online is fine[*], but there are caveats too. Mainly, datas must
be kept on site, which is not fool proof in case of a disaster (fire etc.) ;
and disks being wired to a computer, usually, if the computer goes wrong for
any reason, then all hell may break loose on the poor disks (I witnessed a
faulty RAID card destroying, first, the array hooked on it, then the spares
brought by the compaq tech - it was kinda odd to see the 'I know better than
you do' guy gaze at his fried brand new disks and then the server in a daze,
as if someone was playing a prank on him. But it wasn't funny at the time, so
we didn't laugh).
As a savvy amateur, I would now consider outsourcing my backups to an online
archival company with good fame and warranties ; that probably would mean to
strictly select pictures to reduce the leased storage capacity and the
transfer time, for a digital snap happy, but honestly, who needs to keep a
complete burst of the same action ?
But my dream solution would be to laser-print on a conventional film much like
hollywood does to master film copies from CG graphics. That would be both
durable and versatile. Won't happen in my lifetime, I suppose. Alternatively,
I would consider solid state devices, but it's been more than 20 years
they're due to become economical and yet, the closest we get are 'small' usb
keys.
[*] shelving a hard drive is a very bad idea, after a couple of years, chances
are high it won't spin up because the internal lube has dried. This generaly
fries the main motor. And even if it works, there are then chances that the
magnetism has faded away, leaving nothing but an empty medium.
--
Manuel Viet
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