Had a situation at work where I had to remind myself of something so that means it’s time for a new blog post.
--- JUNOS 12.3R3.4 built 2013-06-14 00:09:12 UTC
---
--- NOTICE: System is running on alternate media device (/dev/ad1s1a).
---
fluong@tickle-me-elmo-re0> show system storage | no-more
Filesystem Size Used Avail Capacity Mounted on
/dev/ad1s1a 3.5G 283M 3.1G 8% / <<<<<
devfs 1.0K 1.0K 0B 100% /dev
/dev/md0 41M 41M 0B 100% /packages/mnt/jbase
/dev/md1 32M 32M 0B 100% /packages/mnt/jkernel64-12.1R1.9
/dev/md2 73M 73M 0B 100% /packages/mnt/jpfe-X960-12.1R1.9
/dev/md3 5.0M 5.0M 0B 100% /packages/mnt/jdocs-12.1R1.9
/dev/md4 78M 78M 0B 100% /packages/mnt/jroute-12.1R1.9
/dev/md5 28M 28M 0B 100% /packages/mnt/jcrypto64-12.1R1.9
/dev/md6 46M 46M 0B 100% /packages/mnt/jpfe-common-12.1R1.9
/dev/md7 388M 388M 0B 100% /packages/mnt/jruntime-12.1R1.9
/dev/md8 7.9G 22K 7.2G 0% /tmp
/dev/md9 7.9G 15M 7.2G 0% /mfs
/dev/ad1s1e 394M 42K 390M 0% /config
procfs 4.0K 4.0K 0B 100% /proc
/dev/ad1s1f 18G 2.3G 14G 14% /var
Here’s the initial scenario. Routing-Engine re0 is booting from alternate media. IN MOST CASES this means a compact-flash on the routing has gone bad and has to be replaced by RMA, but in this case I happen to know that it’s a new RE and we had a USB install that went south. Keep this in mind and know that your mileage may vary with this one.
Other interesting considerations for this scenario is that for this router, a remote hands technician is not on site so we don’t have cheap easy options to do another USB install. Luckily JUNOS provides a means to rewrite the image on the compact-flash if you’re able to boot off the HDD/SSD: “request system snapshot partition”
{backup}
root@tickle-me-elmo-re0> request system snapshot partition
Clearing current label...
Partitioning compact-flash media (ad0) ...
Partitions on snapshot:
Partition Mountpoint Size Snapshot argument
a / 671MB root-size
e /config 400MB config-size
f /var 2GB var-size
Running newfs (671MB) on compact-flash media / partition (ad0s1a)...
Running newfs (400MB) on compact-flash media /config partition (ad0s1e)...
Running newfs (2GB) on compact-flash media /var partition (ad0s1f)...
Copying '/dev/ad1s1a' to '/dev/ad0s1a' .. (this may take a few minutes)
Copying '/dev/ad1s1e' to '/dev/ad0s1e' .. (this may take a few minutes)
The following filesystems were archived: / /config
{backup}
root@tickle-me-elmo-re0> exit
We verify that the compact-flash is in the boot list before rebooting.
root@tickle-me-elmo-re0% sysctl machdep.bootdevs
machdep.bootdevs: usb,compact-flash,disk1,disk2,lan
root@tickle-me-elmo-re0% cli req sys reboot
*** FINAL System shutdown message from root@tickle-me-elmo-re0 ***
System going down IMMEDIATELY
When your router boots next time, you should be able to verify that the root “/” partition is /dev/ad0xxx (for RE-S-1800). (marked below with “<<<<<<”)
fluong@tickle-me-elmo-re0> show system storage | no-more
Filesystem Size Used Avail Capacity Mounted on
/dev/ad0s1a 3.5G 272M 2.9G 8% / <<<<<<
devfs 1.0K 1.0K 0B 100% /dev
/dev/md0 40M 40M 0B 100% /packages/mnt/jbase
/dev/md1 19M 19M 0B 100% /packages/mnt/jkernel64-11.4R3.7
/dev/md2 60M 60M 0B 100% /packages/mnt/jpfe-X960-11.4R3.7
/dev/md3 5.0M 5.0M 0B 100% /packages/mnt/jdocs-11.4R3.7
/dev/md4 78M 78M 0B 100% /packages/mnt/jroute-11.4R3.7
/dev/md5 28M 28M 0B 100% /packages/mnt/jcrypto64-11.4R3.7
/dev/md6 45M 45M 0B 100% /packages/mnt/jpfe-common-11.4R3.7
/dev/md7 382M 382M 0B 100% /packages/mnt/jruntime-11.4R3.7
/dev/md8 7.9G 18K 7.2G 0% /tmp
/dev/md9 7.9G 744K 7.2G 0% /mfs
/dev/ad0s1e 393M 44K 362M 0% /config
procfs 4.0K 4.0K 0B 100% /proc
/dev/ad1s1f 18G 1.7G 15G 10% /var