Patent ID: 7120767

Claim:
A snapshot creating method in a storage system including a file server and a disk apparatus, said snapshot creating method comprising: (a) a step of determining whether a target for a write as a snapshot from a first data storage into a second data storage specified in said file server by a user is of a directory or a file; (b) a step of specifying a block with regard to said file or said directory; (c) a step of selecting a further block when there exists said further block related with said block with regard to data therebetween to add said further block to said block and deleting therefrom an in-no-use block; (d) a step of instructing, from said file server to said disk apparatus, said block targeted whose snapshot data should be generated, (e) a step of, in said disk apparatus, if there occurs an updating request for operational data in said first data storage, confirming whether or not a block to be updated-data written-in destination in an operational data storing region of said first data storage has been targeted for a write within said block, (e1) a step of, if said block has not been targeted, instructing a disk controller to write updated data into said operational data storing region, (e2) a step of, if said block has been targeted, confirming whether or not said specified block had been copied into a snapshot data storing region before, (e2-1) a step of, if said specified block had been copied before, instructing said disk controller to write said updated data into said operational data storing region, (e2-2) a step of instructing said disk controller, if said specified block had not been copied before, to copy pre-updated data into said snapshot data storing region, said pre-updated data existing in said operational data storing region, (e2-2-1) a step of receiving said instruction of copying said pre-updated data, and confirming whether or not said snapshot data storing region has been ensured, (e2-2-2) a step of, if said snapshot data storing region has not been ensured, ensuring said snapshot data storing region, (e2-3) a step of copying said pre-updated data into said snapshot data storing region, and generating simultaneously a block-address correspondence table if necessary, and (e3) a step of writing said updated data into said written-in destination block in said operational data storing region.