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If I watch movies directly off my USB Flash Drive, will the many reads somehow cause the drive to deteriorate faster? Or is there any other harm in doing this?

My alternative is copying the movie to my hard drive. Would that be better?

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4 Answers 4

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A simple check on Wikipedia can help a lot:

The method used to read NAND flash memory can cause other cells near the cell being read to change over time if the surrounding cells of the block are not rewritten. This is generally in the hundreds of thousands of reads without a rewrite of those cells. The error does not appear when reading the original cell, but rather shows up when finally reading one of the surrounding cells.

So indeed reading from a flash memory will cause it to rewrite some blocks every now and then. Writing to a flash memory happens block wise, and every block can only be rewritten a certain amount of times (actual number differs). But considering that this number is quite high, the drive manages (wear leveling) the writes to be evenly spread across the drive, and only every 100th or so read uses a write, your drive will probably die of other reasons before. Or you will just dump it, because it has gotten too small.

So my recommendation would be: As long as the drive is fast enough, use it instead of the hard drive, unless you want the movie on the hdd anyway.

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No. Reads by themselves do not wear out a flash drive; the limit applies only to write operations. However, repeated read operations may necessitate occasional rewriting as noted by Walter Maier-Murdnelch.

Note, however, that hard drives have faster transfer rates when they do not need to seek, so it may simply be better to watch the video from a hard drive.

As a side note, the number of write cycles a flash memory block can sustain ranges from less than 5,000 to 1,000,000, depending on the process--flash ICs manufactured using processes with smaller nanometer values wear out faster (25nm flash memory is limited to about 3,000 write cycles). To mitigate this limitation, flash drives use wear leveling to spread writes across the flash memory IC to ensure that no one block receives a disproportionate number of writes.

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No, reading from the flash drive will not degrade it. Writing to it, however, will wear out the flash memory eventually.

A note: make sure that your flash drive reads fast enough to play the movie without buffering.

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Yes, it is generally better to watch movies from a HDD.

As for the usb lifespan, it is a general rule that everything(!) you do with it, shortens its lifespan. Try buying two sticks and putting one in a safe in a bank, and using the other on a daily basis. The one used will almost certanly have a shorter lifespan ;) Expecially, if it falls and you step on it.

Otherwise, flash drives have a long enough lifespan for all practical purposes, and it is more probable that actual physical harm will come to them, than that they will die from "material wear" in that time.

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