Creating and maintaining clones in continuous data protection

摘要

In traditional storage arrays, the number of clones permitted inside the storage array may be limited by the amount of available storage. Further, clones stored on the array may require significant storage resources. Thus, the number of clone stored by the storage array may also be limited by the storage system memory and not just by the disk space. Accordingly, example embodiments of the present invention allow for creating and maintaining a plurality (e.g., an unlimited number) of thin asynchronous clones in storage, even if replica storage is capable of storing only a limited number of snapshots. Further, example embodiments of the present invention allow clones to be freely attached and detached from the replication environment for various purposes.

主权项

1. A method comprising:
maintaining a volume at a production site; maintaining a copy of the volume at a copy site; selectively storing a clone of the copy of the volume at the production site, the copy site or a remote storage; receiving an input/output (I/O) sent to the volume at the production site; replicating the I/O to the copy of the volume at the copy site; applying the I/O to the copy of the volume at the copy site and the clone at the production site, the copy site, or the remote storage, and determining a state of the clone of the copy of the volume with respect to the copy of the volume; if the clone of the copy of the volume is in a sync state:
continuing to store I/Os; and if the clone of the copy of the volume is in a syncing state:
updating dirty locations which differ between the clone of the copy of the volume and the copy of the volume by copying data from the copy of the volume to the clone and clearing a dirty bit in a differential bitmap; andupdating a new I/O arriving to the copy of the volume to the clone of the copy of the volume if the new I/O is to a synchronized area.