Abstract: Methods and apparatus for modifying a backup data stream to be provided to a fixed position delta reduction backup method are disclosed. When a data stream is received, the data stream may be parsed into a plurality of logical components, where each of the logical components includes one or more data blocks. Missing data blocks may also be detected in the data stream, and therefore may be detected in each of the plurality of logical components. For instance, each of the logical components may be separated into a separate data stream for which missing data blocks may be detected. A temporary data block is then inserted where each missing data block is detected (e.g., in each of the plurality of logical components). In this manner, inefficiencies introduced into a fixed position delta reduction backup process as a result of new or deleted data in a system implementing a plurality of data blocks which may be stored in the form of logical components are eliminated.

Abstract: Methods and apparatus for performing adaptive compression are disclosed. A data stream is divided into a plurality of data segments. When one of the plurality of data segments is compressed, it is determined whether the compression has been successful. When the compression has been successful, a data segment in proximity to the compressed segment (e.g., the next data segment in the plurality of data segments) is compressed. However, when the compression has been unsuccessful, one or more of the plurality of data segments are skipped (i.e., not compressed) before compression is attempted on another one of the plurality of data segments. When a data segment is compressed, the compression algorithm (and any associated parameter(s)) that is applied is selected based upon a variety of factors, such as the length of the data segment, CPU speed, CPU availability, and/or data throughput such as the network bandwidth or network availability (e.g., where data is to be transmitted via a network interface).