> Dhruba told me modification times of directories are not persistent, that is, on namenode restart they are set to the latest modification time amongst the files they contain.
I just have checked the codes. It seems not true.
Also, DistCp works on general FileSystem. It should not depend on a particular implementation.
> If we get atime inside the if, it will be the copy time (last access after copying the file) instead of the latest access time before copying, which is what we need for migration.
FileStatus is a local object. Once it has been obtained from a FileSystem it remains unchanged even the actual status of the file is changed. So the atime inside the if-statement will be the latest access time before copying since getFileStatus is called before copying.
BTW, there is a white space change in the patch, could you remove it?