FlashSnap and FastResync

Veritas FlashSnap provides the ability to create and maintain the on-host point- in-time copies of volumes that are integral to the snapshot solutions. Both the original and snapshot volume may consist of multiple physical devices, as in the case of RAID 0+1 (Mirrored Striped) volumes. FlashSnap cannot be used with software RAID-5 volumes.

FastResync is a FlashSnap feature that optimizes the resynchronization of a snapshot volume and its original volume. FlashSnap uses FastResync technology to track the changed blocks in an original volume after a snapshot is detached. A Disk Change Object (DCO) volume is automatically created to store a record of these changes. When the snapshot volume is resynchronized with the original volume, only the changed data blocks are written to the snapshot volume. This greatly reduces the time and performance impact of resynchronization which means that a snapshot set can be refreshed with minimal impact to production.