One of the shortcomings of flash drives is that the read/write cycles are limited and many sources suggest that flash drives are not suitable for frequent reads and writes operations (e.g. using a journaling file system). Out of curiosity, I decided to test it myself to see how many read/write cycles can a typical flash device handle.

I wrote a little program a couple of weeks ago that would perform writes and reads at sector level (lower level then using the file system, since the OS might allocate different sectors for the same file being written over and over. I think this approach might be more accurate) continuously until errors were detected. The program cycles from byte 0 to 255, and after each write, a read is performed to verify that the data was written correctly. To prevent any possible caching, the byte is incremented (e.g. the first time writes 0, the second time writes 1 and so on) each time and cycled back when it reaches 255.

When I started the program, I was expecting that errors to show up pretty soon since the drive I used in the stress test was relatively tiny (64MB) compared to modern standards. After running the test for a day, I did not see any errors… And after two weeks and some nearly 10 million cycles, I still see no error. To verify, I reformatted the drive and using chkdsk /r to see if Windows reported any bad sectors, and it didn’t.

I probably could just let the program run and check the log later until I find that either a read or a write operation fails, but it is pretty clear at this point that the durability of flash drives is pretty sound. The only thing I found at the end of the test is that the transfer rates of the flash drive had dropped a little bit (which should happen as the read/write cycle increases).

What I want to conclude here after my preliminary test is that there is really no need to worry about using flash drives for frequency writes and reads (e.g. using it as a drive that contains the OS). Just like the life of an overclocked CPU might be shortened a little bit, the life of a flash drive will be shortened under frequent usage. But chances are that the drive will live long after you replace it with one that has hundreds times more capacity and cost significantly less…

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