Manuel Viet wrote:
>
> 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.
I think your conclusion is logically flawed and unnecessarily gloomy. If
one assumes that the accelerated aging tests are in the right range, een
if the truth turns out to be 30-40 years, instead of 70-100+ years, it
doesn't matter if there are errors in the writing. If it can be read
today and doesn't deteriorate in say 30 years, then it should be
readable then, as nothing has changed. The errors that didn't cause
trouble before shouldn't later.
If one instead assumes a slow, steady deterioration that increases
errors over time, then the number of initial errors is important, but I
don't think that is a major consideration with the gold+Mutsui dye
disks. It seems far more likely that the data will be transferred to a
new medium before there is any medium failure.
> 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.
>
And yet, tapes are really terrible for home users. My experience was
that they are noisy, slow and incredibly awkward to use. So bad that I
really didn't use them. An unused system doesn't do any good. So for me
a system has to be practical in use. Even the serious tape backup
systems tehy used in the large IT operation where I used to work weren't
completely reliable.
>> But I think several hard drives are a more attractive option. I saw a
>> 250GB (I think) drive the other day going for $59 with rebate. You can
>> buy a couple of these for the price of 100 MAM-A gold CD's. A lot
>> faster and less hasssle too.
>>
>
> Keeping datas online is fine[*], but there are caveats too. Mainly, datas
> must
> be kept on site, which is not fool proof in case of a disaster (fire etc.) ;
> and disks being wired to a computer, usually, if the computer goes wrong for
> any reason, then all hell may break loose on the poor disks (I witnessed a
> faulty RAID card destroying, first, the array hooked on it, then the spares
> brought by the compaq tech - it was kinda odd to see the 'I know better than
> you do' guy gaze at his fried brand new disks and then the server in a daze,
> as if someone was playing a prank on him. But it wasn't funny at the time, so
> we didn't laugh).
>
In the model Chuck describes and I use, the backup disks are only on
when doing backup or restore. They can't be harmed by anything like a
virus when turned off. And they are used regularly, but very lightly,
the optimum use for longevity. they don't wear out and don't sit unused.
It's not perfect, but the risk/$ ratio is good.
> 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 ?
>
I can see that for a small number of very special images. I suspect I
shoot more than you do. Even with duplicates removed, "m accumulating
gigabytes of images at a troublesome rate. At current prices, I think
HDs are the most practical and cost effective BU solution for single
home users. I ran the numbers before buying a 500gb external drive. The
difference between the cost of gold DVDs for that much data and the
drive was very small and the utility difference is huge.
> 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.
Already happened and gone by. I supose there are still film printers
around, but it's a moribund market. CH used to have one and would burn
slides from digital files, but I think he gave it up?
> 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.
>
Whatever shows up next really doesn't matter, I'm just trying to
maintain some back-up until the next thing comes along, be it solid
state on silicon or crystallographic encoding that will keep all human
knowledge in a little piece of salt.
Moose
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