We mention all this as once again the differences between the X20 and the X18, or even X20 vs X16, are more in line with refinements on a theme rather than paradigm shifts. Much like the X18, the X20 offers the same excellent 550TB per year workload rating. Same MTBF ratting of 2.5M hours. The same controller. The same 256MB worth onboard cache for the MTC to work its magic (albeit it is now Samsung DDR3-1600 branded instead of Micron DDR3-1600). Same Helium filled chassis. Same underlying PMR+ technology. Same vibration sensor hardware.
About the only things that have changed from one generation to the next is the size of the PCB (now even smaller and yet fancier looking) and the density of the platters. With the X16 generation Seagate used (up to) nine platters with a density of a bit over 1.8TB per platter. With the X18 that density was boosted to 2TB per platter. For the X20 Seagate has pushed it to 2.22TB… or an amazing 1.11TB per side or an aerial density of 1.3TB per square inch.
