I am not sure whether it is a feature or not (maybe not). But currently there are some problems of timestamps on OST.

1) If use ‘lfs setstripe’ to create a file, the OST object(s) won't have any atime/ctime/mtime
2) Writing to an OST object will update atime to zero. However, atime should only be updated when reading the file. And, the value of atime shouldn't be updated to zero in any sense.
3) Reading an OST doesn't update the atime.

So, is there any special reason of these behaviors? I understand it won't cause any problem to the POSIX semantics on Lustre client. And we can even avoid performance degredation by using noatime on OST. But we need to make sure everything is behaving in the way that we expect.