# Higher vulnerability to certain types of effects, including abrupt power loss (especially DRAM based SSDs), magnetic fields and electric/static charges, in comparison to normal HDDs (which store the data inside a Faraday cage).
# Limited write cycles – flash-memory storage will often wear out after 300,000-500,000 write cycles[citation needed], while high endurance flash-memory storage may have an endurance of 1–5 million write cycles (many log files, file allocation tables, and other commonly used parts of the file system exceed this over the lifetime of a computer[citation needed]). Special file systems or firmware designs can mitigate this problem by spreading writes over the entire device (so-called wear levelling), rather than rewriting files in place. This problem is being improved all the time, with consequent increases in expected lifespans. Today's drives can last up to 20 years with average usage.[8] An example for the lifetime of SSD is explained in detail here. SSDs based on DRAM, however, do not suffer from this problem.