The Hard Disk Drive industry is more than 50 years old. Over that time period, it has faced a lot of turmoil, uncertainty, price volatility, demand and supply imbalances, technological challenges, limitations to its technological limits, etc.  More recently, however, the hard disk drive (HDD) market has consolidated itself to just a handful of players and with the recent announcement of Western Digital’s plans to purchase Hitachi Global Storage Technologies (GST) there will be only four primary vendors in the HDD Industry: Samsung, Seagate, Toshiba, and Western Digital.  Combine Western Digital’s 2010 share with Hitachi’s and it approaches  50% of total available market for units shipped, says In-Stat.  
 
“Western Digital’s acquisition of Hitachi GST further consolidates the hard drive industry and is certainly a positive move for Western Digital,” says Norm Bogen, VP Research at In-Stat.  “It jump starts WD’s penetration into the Enterprise market where its share prior to the acquisition was 1% and after it will be 24%, second only to Seagate.”
 
Recent Research by In-Stat found the following:
Before the acquisition, the top 4 HDD vendors include Hitachi GST, Samsung, Seagate, Toshiba, and Western Digital. Western Digital had overtaken Seagate as the largest HDD manufacturer for the first half of 2010. 
HDDs have maintained a strong competitive position in many applications against SSDs (Solid State Drives), providing storage at a tenth of the price on a cost/megabit basis.
Drive capacities are growing at a rate of 40% per year.
The industry is expected to cross the 1 Tb/sq. inch threshold in the 2012-2013 timeframe.  
The demand for 2.5-inch mobile/portable drives keeps growing at a faster pace and has outstripped the TAM for desktop drives.
Cloud storage shifts some of the requirements for massive storage on a PC device to one in the Cloud with a companies like Amazon, Microsoft, and Google.