EX3300 JunOS 15.1R5.5 won't boot to single user mode
After upgrading to15.1R5.5, our EX3300s no longer can boot to single user mode with "boot -s" from the boot-loader prompt. Instead, the console shows what looks like the usual process, but then the switch shuts down and restarts.
On a switch that still has 12.4 on the alternate slice, after the "boot -s" fails on the 15.1 slice, you can try it again on the 12.4 slice, and get single user mode there; but once both slices are upgraded to 15.1R5.5, then you will just reboot in a loop each time you try "boot -s" . Doing just "boot" boots normally.
Is this a known bug? I've opened a ticket with my first-level provider, but haven't heard anything official from Juniper yet. I have seen this behavior on several different EX3300s. (Single user mode works as expected on EX4200s with 15.1R5.5)
Alternatively, I only need single user mode so I can get the switch to run fsck on its /var partition. fsck when the switch is up runs in (NO WRITE) mode, and shows many inode issues on fpc0:/var. Yet, when the switch boots normally, it says, "** /dev/da0s3e FILE SYSTEM CLEAN; SKIPPING CHECKS"
for the partition with the errors.
Thus, is there any way to manually flag this partition as dirty, so that the normal boot will run fsck and fix it?
Or, maybe I should just trash a bunch of files in /var ? I know I've seen some switches rebuild their /var partition from scratch on boot when it is too badly hosed, but I don't know if there's any way to trigger this behavior. Are there any other command line options to "boot" from the boot-loader prompt?