Dear all, I am considering using aufs for my company's embedded system. I would like to have a read-only partition with the factory-installed firmware (i.e. operating system with applications), and a read-write partition (user data and all user-initiated firmware upgraded go here). By using this configuration, I can restore the system by just formatting the read-write partition (reset it to factory state) if anything about user data/firmware upgrade go wrong.
In my initramfs, the read-only partition is mounted as /ro, and the read-write partitions is mounted as /rw. Then these branches are merged to /aufs. Then I move /ro to /aufs/.aufs/ro and /rw to /aufs/.aufs/rw. As a last step, I move /aufs to /, and initramfs would finish its job. That is, after booting up the system, the mount point would be: / - AUFS union of /.aufs/ro and /.aufs/rw /.aufs/ro - read-only partition /.aufs/rw - read-write partition But now I found a problem here. I am unable to ensure clean unmount of these partitions. Every time I reboot the system, there is always some unclean filesystem warning, and seems replaying the journal every time for the read-write partition (I am using ext3, and I always see there are several deleted inodes being cleaned, and). Being an unattended embedded system I am very concerned with it, since it is intended to be a security product, and for security reasons remote support is often impossible, since it would not be connected to the internet. This test is just a new installation and test how aufs works, with very little file IO. I am concerned if the filesystem would go wrong if there are more file IO, since data loss is often unacceptable in our embedded system. Is there any way that unmount the filesystem (or at least ensure the filesystem being clean) at shutdown/reboot? I tried mounting all the partitions read-only but seems it doesn't fix this issue. Sorry for the long mail, but I believe that it would be better to explain my situation clearly and throughly. Thanks in advance. Regards, Yiu-Chung Lee ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone
