Methods for transforming a non-transformed stored logical data object (LO) into a transformed LO are provided. One method includes: a) in response to a respective transformation request, logically dividing the non-transformed LO into a segment and one or more non-transformed subsequent segments, each segment having a predefined size; b) generating a header for the respective transformed LO; c) processing said segment; d) overwriting said segment by said generated header and said transformed segment; e) indexing said transformed segment and said one or more non-transformed subsequent segments as constituting a part of said transformed LO; f) generating at least one index section; and g) updating the indication in the header to point that the non-transformed LO has been transformed in the transformed LO including said generated header, said transformed segment, said one or more subsequent segments including data in non-transformed form and said at least one index section.