According to Digitimes, the issue was caused by the Japan earthquake earlier this year. Texas Instruments and Rensesas factories producing chips used in HDDs were damaged in the tragic quake and the effects on shipments and inventories are just starting to take a toll on production. Although production was restarted shortly after the earthquake, the distribution chain was affected and the plants will still need to recertify their chips.
There is still no word on the scope of the expected shortage, but there is no reason to start hoarding hard drives, as average end users probably won’t be adversely affected.
More here.