When SanDisk quotes their mean time between failures (MTBF), I would
presume they're talking about failures that happen while the card is
actively powered up. I'm not sure that figure would have anything to
do with how long an SDHC or SDXC card will retain data while in an
unpowered state. That latter issue is more relevant to the suitability
of SD cards for long term archiving.
Most SDHC cards are rated to retain their data for ten years "under
normal use", but it's not specified whether 'normal use" is in a
powered or unpowered state.
--Flawn
On Jun 26, 2010, at 4:47 AM, wrote:
> Re: Archiving
> Posted by: "Mitch Hill" wa1ykn
> Date: Fri Jun 25, 2010 4:07 pm ((PDT))
>
> A bit more interesting information about archiving image and sound
> file data.
>
> First,
> At 02:34 PM 6/24/2010 -0700, Philip Tyler wrote:
>> I can across this on a photographic website:
>>
>> http://www.dpreview.com/news/1006/10062301sandiskwormsd.asp
>>
>> Here is the last paragraph, which may be of interest to some.
>>
>> Beyond forensic image archiving, SanDisk expects its SD WORM
>> technology to
>> be widely adopted in crucial applications such as audio recording and
>> long-term retention of legal documents and medical files. For more
>> information, visit www.sandisk.com/sdworm.
>>
>> These 'WORM' memory cards will apparently allow storage up to 100
>> years.
>> Which should be a bit more secure than DVD's or CD's?
>
> I've been following the on going discussions about best and long
> term way
> to archive our files with quite a bit of interest. My approach has
> been to
> use SDHC 8GB cards from Sandisc mainly as these are what I use in
> all my
> digital cameras and LS-11 recorder. I've not really spent any time
> to find
> out if this is wise or not as at some point in the near future, I'm
> planning a major computer system upgrade and have enough knowledge of
> electronics and data storage that I've not felt the need to make the
> effort.
>
> However, reading Phil's message about the SanDisc worm and its
> projected
> storage of 100 years and this little bell went ding in the grey matter
> somewhere between my ears.
>
> So, I sent an e-mail to SanDisc customer service last night:
>
> "I use Scandisc Ultra and Extreme SDHC cards for both Nikon cameras
> and
> Olympus PCM digital recorders.
>
> How long is it safe to depend on these cards for long term storage and
> archiving of data?
>
> What is the best way to store these cards?
>
> Are they sensitive to heat while stored?"
>
> And today I received the following reply:
>
>> Thanks for emailing SanDisk Technical Support. It is our goal to
>> make sure
>> you have all the resources you need to get the most from your
>> product.
>>
>> Please note that Sandisk cards has 1,000,000 hours MTBF (Meantime
>> between
>> failure). The ideal way to store it is in room temperature.
>>
>> The Ultra cards don't have any temperature rating declared unlike
>> with the
>> Extreme cards that are tested to perform from -25=B0C to 85=B0C (-13=B0F=
>> to 185=B0F).
>
>
> Now, seeing 1,000,000 hours MTBF, a simple calculation (1,000,000/
> (365*24)
> shows that you should expect 114.155 years between failures.
>
> I make the assumption that the only real difference between the
> SanDisc
> WORM and the SanDisc SDHC cards is that you can erase and edit files
> stored
> on a standard SDHC card where as you can not the WORM...
>
> Very interesting sez me, me thinks I'll keep archiving my files on
> SDHC
> cards and not worry about longevity as long as cards are left alone,
> the
> data will outlast me, my children, and probably my grandchildren at
> this
> point...
>
> I suspect the WORM concept is more to favor legal issues where data
> must be
> secure and un-alterable, for most of us, we already have the
> capability we
> need at hand...
>
> --
>
> Thanks,
> Mitch & Shadow...
>
> http://www.4shared.com/dir/UTASxktL/wildlife.html
>
> Shadow's area: http://www.4shared.com/dir/ecfWjyZb/Shadow.html
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