Hello Gaetan, Ga tan Harter: > board_specific_files -> RO |----> Board_specific_mount_folder--> > mounted via nfs > linux_basic_image -> RW | > > And this, for 200 hundreds of board. > (actually 800, but for the 600 remaining, the linux image might even be = > > read only as not given to the users)
Unfortunately I don't fully understand what you wrote. I will try translating your above diagram into linux commands. # mount server:/board_specific_files /board_specific_files # mount server:/linux_basic_image /linux_basic_image # mount -t aufs -o br:/linux_basic_image=rw,/board_specific_files=ro /aufs Am I correct? Particulary the branch order and the permissions are right? Anyway I will try answering. > Questions > --------- > > How would aufs behave in this case? > If one board modifies a file, it's modified in the 'RW' branch, but will = > > the other ones see the modification? > Will it be considered as a "User's Direct Branch Access"? > Do I need to set it to 'ubda=3Dnotify' for all the image? > Will each file be monitored by libnotify 200 times (I for each aufs mount)? If the modification is made on the NFS client via /aufs, then - this is not UDBA - aufs makes the change on /linux_basic_image - NFS client tells the change to NFS server - when another NFS client accesses the file, the NFS server replies the latest data. but your NFS client may cache the data and as long as the NFS cache is valid, you won't see the latest data. If the modification is made on the NFS client via /linux_basic_image, then - this is UDBA - if "udba=notify" is given, aufs detects the change on /linux_basic_image and makes the cached aufs data obsolete. - NFS client tells the change to NFS server - next time when the same NFS client accesses the file, aufs doesn't refer the cached data in aufs (since it was already obsolete) and asks NFS the latest data. but your NFS client may cache the data here. If the modification is made on the NFS server, then - this is not UDBA - when NFS client accesses the file, aufs uses its cached data but asks NFS client whether the data is still valid or not. - if NFS client replies that the cached data is already expired, then the cached data is not used. aufs requests the latest data via NFS client. Hmm, it is hard for me to answer without fully understand how you mount aufs. So I will wait for your answer now. J. R. Okajima ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev
