REDIRECT-ON-WRITE SNAPSHOT MECHANISM WITH DELAYED DATA MOVEMENT

Techniques include receiving a backup request for backing up data on a production VVOL, to which is assigned physical space from storage devices in a first storage tier. When the production VVOL and a snapshot VVOL exist, and a write request is received to a data block on the production VVOL that is shared between the production VVOL and the snapshot VVOL, then the techniques include capturing a snapshot of the production VVOL by redirecting the write request to newly allocated space on the production VVOL, writing new data to the newly allocated space, and storing metadata referring to the original block(s) on the production VVOL. Based on an IO workload threshold, the techniques include copying, in a background process, the original version of the modified block from the production VVOL to a snapshot VVOL, to which is assigned physical storage space from storage devices in a second storage tier.