System and method for performing operations in a multi-class file system without requiring split mirrors. For one or more storage classes in the multi-class file system, operations that require stable copies of the storage classes may be performed without using split mirrors. In one embodiment, read-only data may be assigned and/or migrated to lower storage classes, and operations may be performed on the read-only storage classes without using split mirrors. In one embodiment, to perform an operation without using a split mirror, a write lock of a storage class may be examined to determine if the write-locked storage class has been written to during the operation on the storage class and, if so, the operation may be retried for the storage class. In one embodiment, the file system software may be blocked from enabling a storage class for writing for the duration of the operation on the storage class.