> if i have one large datafile on zfs, make a snapshot from that zfs fs > holding it and then overwrting that file by a newer version with > slight differences inside - what about the real disk consumption on > the zfs side ?
If all the blocks are rewritten, then they're all new blocks as far as ZFS knows. > do i need to handle this a special way to make it > space-efficient ? do i need to use rsync --inplace ? I would certainly try that to see if it worked, and if your access can cope with files being partially edited at times. > typically , rsync writes a complete new (temporary) file based on the > existing one and on what has change at the remote site - and then > replacing the old one by the new one via delete/rename. i assume this > will eat up my backup space very quickly, even when using snapshots > and even if only small parts of the large file are changing. Yes, I think so. I believe this is even more of a problem for a server with Windows clients (via CIFS) because many of the apps tend to rewrite the entire file on save. Network Appliance eventually added an option on their software to let you do additional work and save space if files are substantially similar to the last snapshot. Theirs works on file close, so it's only a CIFS option. ZFS could conceivably do the same for local access as well, but I don't think anyone's tried to work on it yet. -- Darren Dunham [EMAIL PROTECTED] Senior Technical Consultant TAOS http://www.taos.com/ Got some Dr Pepper? San Francisco, CA bay area < This line left intentionally blank to confuse you. > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
