How are files re-saved to disc memory?


I recently set-up a SSD drive and I understand how SSDs work and why one should limit write cycles to protect the SSD.

However, I'm missing a fundamental piece of computer knowledge (Windows XP on NTFS) that may impact the amount of memory cell writing. I can't find the answer by googling!

Q1. How is a re-saved file (e.g. a Thunderbird Inbox, or an existing Word file) dealt with at SSD memory level?

a) Is the original file un-moved from it's original memory allocation, with ONLY the new data (from the resultant shutdown of Thuderbird or save command within Word) located on new memory pages?


b) Is the modified Inbox file or Word file written to completely NEW memory pages?

If the latter, then a continuously modified file (like an Inbox or email folder - that could also be very large in size) will keep using up new memory, hence reducing the life of the SSD.

I would therefore be grateful if anyone could either answer this 'simple' question and/or point me to some technical sites that have the information.

Many thanks
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  1. I don't know for certain, but I would imagine it uses the same space. However, I think you are greatly over concerning yourself with write cycles to your ssd. People seem to get so caught up trying not to use the drive that it doesn't make sense to use one in the first place.

    My suggestion would be to use it like you would any other drive, just make sure its running on AHCI, that trim is working properly, and go about using your super responsive system.
  2. Hi,

    Thanks for the reply and I agree, I am being a bit over-protective of the SSD!

    Out of interest I posted the question on an OCZ forum and got the following reply:

    "The short answer is if a file is modified the complete file is rewritten to a different area of NAND."

    With that in mind, doing some sums, using a 5000 write cycle limit (often quoted for MLC NAND cells):

    40Gb*5000 = 200,000Gb

    Over a 10 year life:

    Daily writes = 200,000/10*365 = 54.8Gb.

    I'm assumming 54.8Gb per day is a fairly high number for a PC user (up to 8 hours a day)??

    I have disabled the XP SWAP file and moved all Internet browser cache folders to a second HDD/RAM disk.

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