SSD drive lifespan vs HHD

SSDs have far longer lives than HDDs. The big difference is that is an SSD has a memory chip failure then the entire SSD is compromised. This is not usually the case for an HDD. SSDs also need some sort of garbage collection, TRIM, or they tend to slow down a great deal with use. Fortunately, this is less of an issue with modern SSDs and the availability of third-party TRIM utilities which are needed with non-Apple SSDs and OS X.

I have a couple of Samsung 840 Pro SSDs which come with a 5-year warranty. I also have working HDDs which are 5+ years old. If the mechanical issues are detrimental to HDDs, SSDs have there Achilles heel in heat and wear-leveling.

I don't know about SSD's right now.I have had two off brand ssd's that have failed the first one in my desktop failed at 31 days. The company didn't replace it, It was a day over the 30 day warranty. I don't think ssd's have been on the market long enough where we can accurately tell there lifespan.

Tried and tested HDDs can last more than 15 years. The SSD are volatile and a mishap in it's circuitry means permanent loss of data. Because there are no moving parts, if it fails there is no way of accessing the memory or porting it to another device. All its components are at micro level. SSDs are the new kid on the block designed to fail so that you can buy a new computer soon (my opinion).

Unlike SSDs, if a HDD fails you can do "CPR" or a "heart transplant" and get it going to recover the essentials.

SSDs use a complex write algorithm to manage disk space and mitigate memory sector failure. Writing and rewriting is what causes failure in SSDs because it involves charging and discharging PN junctions on the SSD. As observed, these types of memory will become slow as data accumulates and rearranging the data to maximise efficiency is not that easy like defragmenting an HDD.

If you are worried about things failing, you can buy a 1TB external HD and use it as your time machine backup.