Patent ID: 7558930

Claim:
A method for providing write protection in a data storage system, said system providing a first type of write access for accessing a first device and a second device in the storage system, and a second type of write access for accessing the second device and a third device, the method comprising: providing a first type of write protection for prohibiting write access to a data unit stored in the second device; providing a second type of write protection for prohibiting write access to a data unit group, said second type of write protection including a first mode to prohibit both said first type of write access and said second type of write access, and a second mode to prohibit only said first type of write access against data units in the second device; determining whether or not a target device is accessible by both the first type of write access and the second type of write access; invoking the first mode responsive to at least one data unit of the data unit group having an associated indication of unallowable write access if the target device is accessible by both the first type of write access and the second type of write access; and invoking the second mode if the target device is not accessible by both the first type of write access and the second type of write access, wherein the data unit group is a block or file system, the data unit is a file, the first type of write access is a block-level access, and the second type of write access is a file-level access.