Patent ID: 9081842
Filing Date: 2015-07-14
Classification: G06F

Abstract:
1. A method to provide synchronous and asymmetric active-active-active access to a first storage volume using a global cache coupled to a first, second and third virtual storage volumes comprising: replicating asynchronously the first storage volume at a first site to a second storage volume at a second site; mirroring the first storage volume with a third storage volume at a third site, either one of the first storage volume or the third storage volume having primary storage functionality; virtualizing the first storage volume with the first virtual storage volume; virtualizing the second storage volume with the second virtual storage volume; virtualizing the third storage volume with the third virtual storage volume; receiving a request to read a location on the first storage volume at the second site; reading the location at the first storage volume or the third storage volume if the global cache has a phase value for the location; reading the location at the second storage volume if the global cache does not have a phase value for the location; and tracking locations in the secondary storage volume that do not mirror the first storage volume, wherein the tracking comprises: