I've used the COMPRESS feature for quite a while and you can flip back and forth without any problem. When you turn the compress ON nothing happens to the existing data. However when you start updating your files all new blocks will be compressed; so it is possible to have your file be composed of both compressed and uncompressed blocks! This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss