Comment 4 for bug 1410363

As discussed on IRC this sounds like the re-appearance of the issue where some data which is used by cloud-init was present on the second disk. After boot and setup this ends up in a state where one succeeds in running unmount but the jbd process related to the mount remains stuck.

Last time this seemed to stop being reproducible at some point. So we had the same issue with 3.16 kernels, too. But we don't know exactly when it gets triggered.

In order to do experiments locally we need to know exactly what kind of data is on vdb. All the documents I find for cloud-init claim to require either an iso fs or vfat for instance data. And for OpenStack it sounds like only using network. So what would be the contents of vdb and is there what do we need to comply with when creating the fs (I think Trusty running on the creating host, any fs label?).