QUOTE(abubin @ Dec 3 2013, 02:18 PM)
just a reminder to those planning to get secondhand SSD. Note that all SSDs have limited lifespan. Especially those made with MLC chips. Those more expensive using SLC will last a lot longer but price very very high.
So I can say nearly all are made using MLC which some said have 3000-5000 writes only. Whatever it is, just don't pay too high for secondhand SSDs.
Take note also TRIM is very important to make the drive last longer and long term performance.
i appreciate your good intention. it's good to remind people about getting second-hand ssd's, because there are definite risks in obtaining one.
however to avoid giving people misconceptions on ssd's, i would like to add the following:
* '.. especially those made with mlc chips' - currently, we have 3 types of nand flash chip in ssd's: slc, mlc, and tlc. slc was said to have 100,000p/e cycles; mlc has 3,000-5,000 p/e cycles, and tlc has 1,000 p/e cycles. (actually we have another type called e-mlc, which was said to have about 20,000 to 30,000 p/e cycles) in general, most of current consumer and enthusiast ssd's are made with mlc chips.
* '.. which some said have 3000-5000 writes only' - this is supposed to mean mlc have '3000-5000 p/e cycles' (p/e is program/erase). this can translate into different outcomes that are depending on the actual capacity of the target ssd being used and how it is used (usage).
now imagine you have a 4gb ssd. you save a 4gb movie to this ssd. you watch the movie, and then delete it. you empty the recycle bin which triggers the trim command. the ssd's garbage collection now erases the movie from the ssd. 1 p/e cycle has now been used. (i.e. if you have 120gb ssd, 1 p/e cycle means you write and erase 120gb of data one time)
reading data has no effect on p/e cycles; only writing data and erasing data have.
some examples can be found here:
http://www.anandtech.com/show/6459/samsung...nce-of-tlc-nand