I spent some time today looking at the release notes for Enginuity code 5874.207.166, which presumably is the one that brings the much lauded Fully Automated Storage Tiering (FAST) into general release on V-Max. Just above the FAST paragraph I found the following:
Symmetrix Virtual Provisioning Space Reclamation reduces capacity requirements and total cost of ownership by automatically reclaiming chunks (768 KB track groups) that contain all zeros. This is most effective when used on volumes after thick-to-thin migration or replication.
So, it seems that V-Max now supports features previously only seen on 3Par InServ, HDS USP V and HP XP – that is the ability to reclaim empty “zeros” of data from LUNs – otherwise known as Zero Block Reclaim.
I don’t remember EMC mentioning this little fact as part of their big FAST announcement. In fact, looking back over Barry B’s posts, here’s a link to a post from July in which Barry indicates (quoting again);
I cannot confirm nor deny that VP will support one or more unused space reclamation approaches in the future.
So do EMC just see ongoing space reclamation as a BAU activity, not worthy of an announcement? I’m surprised that this would be the case. Reclamation of “empty” storage is incredibly important when migrating from thick->thin storage environments. Hitachi quote around 40% savings from using ZPR after a migration to thin provisioning on USP V.
Perhaps EMC don’t want us to know that migrating to V-Max can actually reduce the amount of storage in use. After all, its not good for hardware sales, is it?
By the way, EMC, please feel free to comment on this new feature and how easy it is to use. I’d be interested to discover how it is implemented.