Lost disk from Junos boot order

26 01 2011

I keep forgetting how to do this, hence a note to self…

Every so often Junos routers (in the latest case) an MX seem to lose their hard disk. This can go unnoticed and when you come to do something like upgrade the software, you run into disk space issues since one is much smaller than the other.

To check this out do the following:

1. start shell
2. sysctl machdep.bootdevs

This second command will tell you the order in which devices are booted from. If ‘disk’ is absent from that list, you need to add it back in and reboot the routing-engine. Do the following:

1) su root (you’ll need the root password for this)
2) sysctl -w machdep.bootdevs=usb,compact-flash,disk,lan
3) Exit from the shell and reboot the RE.

The above is for an MX960 with an RE-2000 installed, and the device names change a bit depending on what you are using. Best to check it against another working system if you can.

Here’s a cut-and-paste from my MX960:
root@MX960-RE1% sysctl machdep.bootdevs
machdep.bootdevs: usb,compact-flash,lan
root@MX960-RE1% sysctl -w machdep.bootdevs=usb,compact-flash,disk,lan
machdep.bootdevs: usb,compact-flash,lan -> usb,compact-flash,disk,lan
root@MX960-RE1% exit
% sysctl machdep.bootdevs
machdep.bootdevs: usb,compact-flash,disk,lan
% exit



One response

3 12 2012
Fredrik Lönnblad


Do you know or have an idea of why this happends?

Best Regards
Fredrik Lönnblad

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