SSD durability question

[rtyhgn85]

I am thinking about buying an SSD to replace my HDD. Am I right in thinking that a larger SSD will last much longer than one with less space? Let's say you have a 64 GB SSD with Trim with an average of 10.000 writes. So in theory, this drive will last 64 GB * 10.000 writes = 640.000 GB = 640 TB of total data? With this calculation, a 128 GB drive should last twice as long (1280 TB)?

 

Thanks

[SYNACK]

That depends heavily on the SSD controller the 10000 write cycle is mean time between failure so it is just a statistical mid point. It depends on the wear leveling of the controller as to whether twice the capacity is twice the durability but it is very unlikely (almost impossible) that the controler would scale perfectly in this regard. Even if it is one of the ones with the latest tech in it you are probably looking at (pulling a figure out of the dark) maybe 25%-50% more long lived.

[Butuz]

Or you could use 2x 64gb drives in raid 0 in order to half the writes on each drive and thus double their life. As a brucie bonus you also get twice the speed!! Handy!

 

Butuz

[Arthur]

Let's say you have a 64GB SSD with TRIM with an average of 10,000 writes. So in theory, this drive will last 64GB * 10,000 writes = 640.000 GB = 640 TB of total data?

It's much more complicated than that since wear levelling algorithms, write amplification factors and the amount of spare NAND an SSD has play a big role...

 

http://www.anandtech.com/show/4159/ocz-vertex-3-pro-preview-the-first-sf2500-ssd/2

 

Also, once you have used up all of the NANDs program/erase cycles it's not the end of the world...

 

Remember that the JEDEC spec states that once you've used up all of your rated program/erase cycles, the NAND has to keep your data safe for a year. So even in the unlikely event that you burn through all 3000 p/e cycles and let's assume for a moment that you have some uncharacteristically bad NAND that doesn't last for even one cycle beyond its rating, you should have a full year's worth of data retention left on the drive. (Source)

 

Many SSD manufacturers have a program which you can use to check how much data has been written to your SSD. Here's what my 160GB X25-M G2 looks like after 6 and 20 months respectively (it was purchased on 27/07/2009). This is with running several VMs from it too.

 

15th February 2010

 

http://i.min.us/ikKLDC.png

 

3rd April 2011

 

http://i.min.us/imXjHE.png

 

If you're looking for a reliable SSD, you should check out Intel's 320 series of drives...

 

http://www.anandtech.com/show/4244/intel-ssd-320-review