SD & SDHC maintenance

polchraine · 2009-04-13T23:48:04+0100

I emailed SanDisk earlier today about refreshing data on a SD or SDHC card and their response was: ... we recommend that you format the card once in a while. Please be aware that formatting is a normal and necessary method of drive maintenance and repair, and simply NOT formatting periodically can cause a drive to slip into failure due to the backup, and clutter of residual data. After formatting, you can transfer the files back to the card. Doing this will refresh the card's system. So, will that cause the directory/folder numbering to be reset on each card? And how often is once in a while? Monthly? Yearly? after filling te card 10/200/500/1000 times?

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terje-l terje-l

1384 posts
18 years
Horten,
Norway

Posted 16/04/2009 - 09:45 Link

Oggy wrote:
That's right as far as I know. You remove it's entry from the File Allocation Table. This file holds information on which sectors are used and which are free. Basic recovery programs work by actually reading all sectors, rather than looking at the FAT. This is why if you if you accidentally delete something, you should immediately stop using that media until you can you can unleash recovery software on it. The information is still there until it is overwritten.

Actually, deleting a file just replaces the first letter of the file name in the FAT with the value E5 (hex), which means file previously deleted - space free to use.

An undelete program searches for this value and gives you the option to insert a valid character, thus restoring the file name and the file, providing nothing else has been written to the disk in the meantime.

Best regards
Terry

K20D, Optio I10, DA 18-55 1:3.5-5.6 AL II, A 1:1.7/50, D FA 1:2.8/100 Macro, Sigma 70-300 1:4-5.6 APO DG Macro, Pentax AF 360FGZ