Patent ID: 8316289

Claim:
Storage apparatus comprising a data store; a data input; and a data processor arranged to: receive from the data input a block of data to be stored at an append point after sequential data comprising one or more stored blocks of data; retrieve an integrity measure, of one or more stored integrity measures that are associated with one or more respective points in the sequential data, said retrieved integrity measure being associated with a point at or preceding the append point; calculate a new integrity measure using the received block of data and the retrieved integrity measure, wherein the retrieved integrity measure has previously been calculated independent of the calculation of the new integrity measure; and store the received block of data and the new integrity measure in the data store, in addition to at least one stored integrity measure that is associated with a point in the data at or preceding the append point, wherein subsequent deletion of the stored block or the new integrity measure does not require recalculation of the one or more stored integrity measures that are associated with one or more respective points in the sequential data.