Previously we would always re-mount the ramdisk by default. The issue was that the user might accidentally delete Alluxio data that they want to keep. So we changed it so that we don't mount by default, and error out if the ramdisk doesn't exist. Now the user needs to use either "SudoMount" or "Mount" when they start Alluxio for the first time - omitting the mount option no longer works. I suggest changing the default behavior from "NoMount" to "SudoMount" and getting rid of "NoMount". This would make ramdisk/mount option more of an internal implementation detail of Alluxio. Users will only need to worry about mount option if they need to use Mount instead of SudoMount.
Seeing as this is an API breaking change, we should target this for 2.0
Wasn’t there a scenario where tmpfs was used instead of ramfs? How would that be triggered?
I don’t think our API gives a way to create a tmpfs. But you can point to a tmpfs and use NoMount to use it instead of ramfs. This usage could be handled by SudoMount/Mount, which can check for either a tmpfs or a ramfs at the tier0 mem path. I think that’s better than having NoMount implicitly mean “use an existing tmpfs”