O> I feel like I understand what tar is doing, but I'm curious about what is it > that ZFS is looking at that makes it a "successful" incremental send? That > is, not send the entire file again. Does it have to do with how the > application (tar in this example) does a file open, fopen(), and what mode > is used? i.e. open for read, open for write, open for append. Or is it > looking at a file system header, or checksum? I'm just trying to explain > some observed behavior we're seeing during our testing. > > My proof of concept is to remote replicate these "container files", which > are created by a 3rd party application.
ZFS knows what blocks where written since the first snapshot was taken. Filenames or type of open is not important. If you open a file and rewrite all blocks in that file with the same content all those block will be sent. If you rewrite 5 block only 5 blocks are sent (plus the meta data that where updated). The way it works is that all blocks have a time stamp. Block with a time stamp newer that the first snapshot will be sent. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
