Patent ID: 8055622

Claim:
A system, comprising: at least one processor; and a memory storing file system software that when executed by the at least one processor performs: managing files in a file system implemented as a tiered storage hierarchy comprising two or more storage tiers for storing mutable data, each storage tier including one or more storage devices, and an immutable data container for storing immutable data, wherein, in said managing files, the file system software performs storing files to and migrating files between the storage tiers according to a policy that includes specifications for storing files to and migrating files between the storage tiers; wherein the file system software comprises an immutable data mechanism that when executed by the at least one processor performs: tracking files in the file system; applying the policy to one or more attributes of the tracked files, wherein the policy specifies particular attributes of files to be migrated to the immutable data container as immutable data; and migrating one or more files in the file system to the immutable data container as immutable data in response to said applying the policy to attributes of the tracked files; wherein the one or more files migrated to the immutable data container remain online within the file system.