> it's not necessarily hard -- you just write the code -- but it's > more fragile to do this kind of exact mirroring, because you > can't make any local modifications without breaking the > mirroring. if you decide you don't want to keep some huge > subtree, for example, or you want to add a few locally > maintained files.
on the other hand, a mirror doesn't really operate at the level of the filesystem. a mirror needs to avoid the normal permission checking. my experience has been that filesystem-level copies tend to have errors in them and the errors increase over time. and the muid is wrong. that's a big deal for us. maybe plan 9 needs dump. i could be out of step here. my basic assumption is that unless a mirror is exact, it's not a mirror. you know, might be missing some files. owners might be different. muid broke. you know, ymmv. if i set up mirrors like that, ever time anyone had a problem with a file, they'd blame me first. > the file system is a good interface -- witness all of plan 9 -- > and if you're going to start working at a lower level i just > think you need a much more compelling reason. the file interface has nothing to do with this problem. it's the arenas that need copying. if you do that, the files will take care of themselves. venti itself doesn't even use 9p. > if your goal is to have a live backup of a system, then some > disk-level thing might be exactly right. but for having a > local mirror of sources, the lsr file and a simple script to > run the cp commands is simple and more flexible. by the way, if the datestamp in the lsr file is not the current day (you know, cp -x), you'll miss the file with the lsr file. - erik
