> In theory - yes. > In practice, there are some caveats. There are some nasty race conditions > that make splitbrain even more dangerous than you might expect. > > Files are versioned. Deleting and re-creating a file causes the version to > be reset. Some programs delete and re-create a file rather than modifying it > (e.g. vi does). This has a number of dangerous side effects. If your > disconnected server has an old version that was incrementally modified (e.g. > log file being appended to), it's version will be high. If you delete and > recreate the file, or do something that will have the same effect (e.g. edit > with vi), the version on the working servers will be reset (low number). > > When the server that dropped out reconnects, it's version will be higher > than the new (reset) version, and it's old file will clobber the new file. > This is not entirely correct. This can *potentially* happen if the two clients (the client who created the first file and the client which re-created the file) are out of sync in time. AFR keeps the client system create time in the xattr and uses that as a major version number (the other thread discusses changing this major number to be equal to the parent dir minor number). If time(system1) - time(system2) < wall_time(file1) - wall_time(file2) then there is no data corruption. avati
