On Thu, Dec 3, 2009 at 12:08 PM, Darren J Moffat <darr...@opensolaris.org> wrote: > Per Baatrup wrote: >> >> I would like to to concatenate N files into one big file taking advantage >> of ZFS copy-on-write semantics so that the file concatenation is done >> without actually copying any (large amount of) file content. >> cat f1 f2 f3 f4 f5 > f15 >> Is this already possible when source and target are on the same ZFS >> filesystem? >> >> Am looking into the ZFS source code to understand if there are sufficient >> (private) interfaces to make a simple "zcat -o f15 f1 f2 f3 f4 f5" >> userland application in C code. Does anybody have advice on this? > > The answer to this is likely deduplication which ZFS now has. > > The reason dedup should help here is that after the 'cat' f15 will be made > up of blocks that match the blocks of f1 f2 f3 f4 f5.
Is that likely to happen? dedup is at the block level, so the blocks in f2 will only match the same data in f15 if they're aligned, which is only going to happen if f1 ends on a block boundary. Besides, you still have to read all the data off the disk, manipulate it, and write it all back. -- -Peter Tribble http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
