Storage Tiering  is the process where frequently accessed data is stored in expensive storage ( Say Storage Tier-1) so to have faster access and less frequently data is stored in non-expensive storage. ( Say Storage Tier-2).

Hence storage tiers could be classified as

• Storage Tier-1 :
  • For faster access of data,
  • Mission critical applications are deployed in storage tier-1 like databases and ERP.
  • Generally  SSD belongs to storage tier-1 hence it is costlier
• Storage Tier-2
  • Not much faster access of data.
  • It is used for storing bulk data
  • Generally HDD belongs to storage tier-2 hence it is less expensive.