Caching inside the host

• Others (sometimes - the same people) attempt to put the cache inside the servers.
• Advantages:
  • Full use of the low-latency of SSD storage.
  • Allows doing the caching at the file-system level.
• Disadvantages:
  • No flexibility in assigning SSD space to servers - needs careful planning and on-going management.
  • PCI-e SSDs (which are faster then SAS SSDs) are not hot-swappable - any need for upgrade means downtime.
  • Not manageable without proper software support (e.g. the storage snapshots won't include data freshly written to the SSD cache).
  • Requires a whole new software stack to really become useful.
• Example: EMC's VFCache ("project lightning"): http://www.emc.com/about/news/press/2012/20120206-01.htm

Originally written by guy keren