Hello Christian, Christian Huldt: > Since there is a considerable difference in size, I would like to "copy > down" changes from > /mnt/newssd to /mnt/olddisk about once a week.
If you mean real "copy-down" instead of "move-down", then it is mostly harmless because aufs handles the top-most file. Even if the same named file is created on the lower branch, it doesn't matter. But the upper writable branch usualy contains a whiteout. After simple rsync, the lower branch will have both of real entry and a whiteout for it. eg. "fileA" and ".wh.fileA". As long as your lower branch is at the bottom of the layer, it will be still harmless (I guess). If you re-order the layers or use the the lower branch for another aufs's upper branch, then aufs will be confused and will not work correctly I am afraid. For such case, you should run auchk for that branch which checks "Illegal whiteout", "Remained pseudo-links", and "Remained temp files" and cleans the garbages such like generic fsck. Moreover, for the dir, it will make aufs busy a little. Generally speaking, when you read a dir via ls(1) or something, aufs tries reading all entires on under the dir on all branches. Here the same named lower entires will be hidden, but the internal aufs work increases. If you mean "move-down", I mean "remove the copied-down files", then simple rsync will be harmful. It will surely confuse aufs. Finally the most recommended way is aubrsync. But it should be used at the system shutdown time (or when the unmounting aufs time). I have a plan to support "live move-down" feature, but I don't know when it will complete. J. R. Okajima ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter
