Method and apparatus for monitoring the quantity of differential data in a storage system

A method for storing a snapshot of a logical volume comprising:

• receiving a snapshot request to produce a snapshot of the logical volume;
• receiving a write request at a time subsequent to receiving the snapshot request, the write request being associated with a first region of the logical volume to be written;
• if the first region had been previously subject to a copy operation, then servicing the write request;
• if the first region had not been previously subject to a copy operation, then performing steps of:
• copying data in the first region to the preservation volume;
• and
• subsequent to the copying, servicing the write request,
• wherein data in other regions of the logical volume which have not been previously copied to the preservation volume and data stored in the preservation volume collectively constitute a snapshot of the logical volume at the time of receiving the snapshot request;
• computing a rate of storage consumption of the preservation volume resulting from copying of data from regions of the logical volume to the preservation volume during a predetermined period of time;
• and
• presenting first information to a user indicative of the rate of storage consumption of the preservation volume.

A method for a storage system configured with one or more logical volumes and operable to perform snapshot processing comprising:

• receiving a plurality of first write requests directed to a logical volume;
• servicing each first write request by writing data associated therewith to the logical volume;
• receiving a snapshot request directed to the logical volume;
• subsequent to receiving the snapshot request, receiving a plurality of second write requests directed to the logical volume;
• for each second write request:
• if a data block on the logical volume that is targeted by the second write request is not identified as being marked, then copying data stored in the data block to a preservation volume and identifying the data block as being marked;
• and
• servicing the second write request by writing data associated therewith to the data block;
• at a time t1 subsequent to receiving the snapshot request, determining how much storage has been consumed by the preservation volume and computing a rate of storage consumption of the preservation volume based thereon;
• and
• presenting first information to a user relating to storage consumption of the preservation volume.

A data storage system comprising:

• a host subsystem;
• a storage subsystem comprising a plurality of physical storage devices, the host system operative to send read requests and write requests to the storage system;
• a first logical volume defined among the physical storage devices;
• a preservation volume defined among the physical storage devices;
• a computer operated process to determine storage utilization information of the preservation volume;
• and
• a display component,
• the storage subsystem operative to perform copy-on-write snapshot processing wherein a first data block of the first logical volume is copied to the preservation volume when a write request from the host subsystem targets the first data block, the first data block being copied to the preservation volume prior to servicing the write request, wherein additional write requests from the host subsystem causes additional data blocks of the first logical volume to be copied to the preservation volume prior to servicing the additional write requests,
• the storage utilization information being determined based on the amount of storage consumed by the preservation volume over a predetermined period of time,
• the storage utilization information being presented on the display component.