Thanks. More bits for the brain.
Winsor
Long Beach, California, USA
On Mar 6, 2007, at 3:29 AM, Chuck Norcutt wrote:
>
>
> Winsor Crosby wrote:
>> I thought it did more than that because of a couple of things. One of
>> the reasons given for reformatting is to map around defects in the
>> memory device. If there is a defect and reformatting is just an
>> erasure then aren't you going to keep running into problems with the
>> defect?
>
> Modern disk drives have a defect table that is used to map out
> defects.
> It's stored on a part of the disk not otherwise used for data or
> directory. Maintenance and use of the table is a function of the
> drive
> itself via the built-in drive controller. The OS knows nothing about
> it. Whether CF cards have an equivalent facility I don't know but
> would
> not be surprised since CF cards are, for all intents and purposes,
> EIDE
> disk drives including a built-in drive controller. CF card
> controllers
> also maintain a usage table to distribute "wear" across individual
> sectors. I haven't seen stats on CF write cycle lifetimes in many
> years
> but it used to be about 100,000 writes per sector. The wear tables
> distribute the usage across all the sectors, ie; sector #1 is not
> always
> in the same physical place. The built-in controller also used to
> be the
> differentiator between CF and some other technologies like XD cards.
> Whether XD cards have changed I don't know but it used to be that the
> camera had to have the controller which meant the camera was
> technologically limited on things like card size so you get to throw
> away the camera instead of the card as the storage size grows. A
> dumb idea.
>>
>> Frequently advice is given to only reformat in the camera and not on
>> the PC. If reformatting just does the equivalent of an erasure, that
>> is, removing the directory information tags, then there is no point
>> that I can see to reformatting in one device rather than another. The
>> very real problems people have not reformatting in the camera would
>> seem to indicate there is more going on than a mass erasure.
>
> When the camera reformats it also adds a small set of folders
> unique to
> the camera. Your PC knows nothing about them.
>
> Chuck Norcutt
>
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