Patent ID: 7725436
Filing Date: 2010-05-25
Classification: G06F

Abstract:
1. A method comprising: operating, in a file server comprising a data processing system, a write out-of-place file system, the file system comprising at least one subset; maintaining a first read-only, persistent point-in-time image (RPPI) of the file system, wherein the first RPPI is created upon a first update of the file system, wherein at least one subset of the first RPPI has a softlock created to indicate an update on the corresponding subset of the file system by the first update of the file system or another update of the file system that occurred before the first update; creating a second RPPI of the file system corresponding to a second update of the file system, wherein, for each subset of the file system updated by the second update, a softlock is created and associated with the corresponding subset of the second RPPI to indicate an update on said subset of the file system by the second update of the file system; determining, for each subset of the file system, whether there are a first softlock created for the corresponding subset of the first RPPI and a second softlock created for the corresponding subset of the second RPPI; deleting the first RPPI of the file system in response to determining that none of the subsets of the file system has a first softlock created for the corresponding subset of the first RPPI and a second softlock created for the corresponding subset of the second RPPI, wherein the second RPPI is not modified; and upon deleting the first RPPI, transferring each softlock created for the first RPPI to the second RPPI such that a softlock associated with a subset of the first RPPI is associated with the corresponding subset of the second RPPI after the transference.