--compress or -z will compress during data transfer what about a variable compression rate? --optimal-compress or -za monitor the speed of the transfer and the cpu throughput and automatically find the optimum compression in almost-real-time with the goal of reduced transfer time i figure you'd have to mark the last block compressed/sent with extra data indicating new blocks are using a different compression strength, and it could work for using multiple algorithms, depending on the data when decompressing, when detecting a new block, it will indicate corruption in the archive, but the extra data will revert the error indication - the `corruption' would only be up until the last block, so the data remains intact, and the new rate/algo can begin after the `failed' block finding the type of data that can be compressed better/faster with different algorithms will also be taken into account just an idea