Patent ID: 9639591
Date: 2017-05-02
CPC Classifications: G06F

Claim:
1. A CAS data storage system comprising: at least one source CAS data storage space, a destination CAS data storage space, and a communication line connecting said source storage space and said destination storage space, wherein input data for storage in said system arrives at said source storage space for storage in said source storage space and replication in said destination storage space, and wherein a hash key of a data item is generated at said source storage space, said source storage space comprising: a hash key storage table configured to store respective generated hash keys in said source storage space to indicate that said respective data item is stored at said destination storage space, wherein the hash key storage table is enabled to contain multiple indexes indicating which destination storage device is associated with respective generated hash keys and data associated with each respective generated hash key, wherein the hash key storage at the source storage space is enabled to provide determination of whether data is stored at the destination storage device; and a hash key inspection unit configured to compare hash keys stored at said hash key storage table against hash keys generated from further data items arriving at said source storage space to determine whether respective further data items are already present at said destination storage device, wherein if a match is made an associated data item is present at said destination storage device and the associated data item is not unique to said destination storage device, said source storage system configured to transfer respective further data items if no match is made to a hash key stored at said hash key storage table, but not to transfer respective further data items if a match is made to a hash key stored at said hash key storage table, thereby only transferring unique data items; wherein the hash key inspection unit is enabled to compare hash keys and make a determination to send an associated data item without communicating with the destination storage device; wherein said source storage space is enabled to utilize write folding on data determined to be sent to the destination storage space.