exciter said:
ok guys after a shock and anger,
i used scanpst.exe which solved the problem forunately!
these programs are good but their problems take too much time!
USB sticks (using flash memory) and flash cards are not reliable media for
permanent storage. Each bit only has so many writes before it becomes
unusable. Flash cards eventually die and far sooner than hard drives.
Anyone that has used their flash card for taking lots of pictures knows that
the cards eventually die (and "eventually" isn't really that long a time,
either). That is why they sell mini-hard drives for toting around when you
are traveling so you can download the pics that you took that day to get
them off the flash card and onto the hard drive. They can die even after
you stopped using them, so taking a bunch of pics and leaving the card in
the drawer for months could result in you losing all those pics. Some
manufacturers, like Corsair, give a lifetime warranty but obviously you use
it after your flash card died. You put your .pst on unreliable media.
Temporarily putting files on a flash card or USB stick is okay to physically
transfer files but don't rely on it for permanent storage. The file is
probably still back on the host from where you copied the file if the copy
on the flash memory is bad. One, or a few, bad bits in a pic isn't disaster
since the loss of a couple pixels usually isn't critical or even noticeable
and the other pics are okay. But the loss of one bit in a file, especially
an executable file, could render it useless (or maybe worse since you no
longer executing the correct code).
There are a lot of digital camera users that are tossing dead flash cards
and yet they don't put anything on the packaging warning users of the
limited usable lifetime of these devices (but then most light bulbs don't
mention their usable lifetime, either). There are only so many programming
cycles to flash memory. You put a lot more wear on the same bits when you
use flash memory as a replacement for a hard drive because of continual
rewriting of those same bits versus taking pictures or recording audio which
usually records sequentially, like a CD. Go read
http://www.sandisk.com/Assets/File/OEM/WhitePapersAndBrochures/RS-MMC/WPaperWearLevelv1.0.pdf.
SanDisk tries to compensate for gradual defects that occur due to repeated
programming of the flash memory. The SanDisk devices are designed for long
usable lifetimes but the compensate for the wear leveling. I don't know
how, if at all, the flash cards or USB sticks handle eventual loss. From
what I've seen of dead flash cards for digital cameras, the same ones you
slide into a slot into your computer and the same technology used in USB
stick drives, the loss is immediate and catastrophic so it appears there is
no compensation.
