Patent ID: 7418465

Claim:
A computerized method of managing a file system for a file server, comprising: receiving a file operation that signals a reservation operation for reserving an additional number of blocks for storing a file of the file system, the file having a file size; computing a first number of blocks needed to accommodate the file size; subtracting from the first number of blocks a second number of blocks already allocated for the file and a third number of delayed allocated blocks for the file to obtain a fourth number of unallocated blocks needed to accommodate the file size; and using the fourth number of blocks to perform a reservation of unallocated blocks for the file for later allocation, wherein said using the fourth number of blocks to perform a reservation of unallocated blocks for the file for later allocation comprises: checking that a number of available blocks in the file system is greater than the fourth number of blocks, wherein an error is returned in a case that the number of available blocks is less than the fourth number of blocks, wherein the number of available blocks in the file system is determined by subtracting a number of allocated blocks, a number of cached unallocated blocks, and a number of reserved blocks from a total number of blocks in the file system, and adding a number of reserved cached unallocated blocks; wherein the file system uses a write anywhere file system layout characterized in that data to be written are written to new blocks instead of being written to blocks previously allocated for said data.