Hmm, two thoughts on this: 1. For anyone interested, didn't VMS do something like this? Perhaps a look at its design and implementation would be useful here.
2. For the per-application issue, there are ways to handle that. First, make a ZFS api for providing file-level snapshots. Then, a library wrapper around the normal syscalls (open,close,read,write,etc) that invokes the zfs apis as needed. Either the wrapper is smart enough to know which app wants which behavior (perhaps even specializing also on the path of the file), or several libraries available for different tasks. Shove it/them in something like LD_PRELOAD and you'd be good to go. As for utility, I think this sort of thing would be fantastic in certain areas. If you can develop the feature set cheap enough, then it's a real win. I haven't touched ZFS's internals (in code or even dev docs), so I don't know what kind of work's required to pull off file-level snapshots. -- H. Lally Singh Ph.D. Candidate, Computer Science Virginia Tech _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
