Recipe 1.18. Creating an Emergency Rescue Configuration
You want to store a copy of a known good and working configuration that you can load in case of an emergency without having to remember which rollback number to use.
When a known stable and working configuration is loaded and running on the router, save it as the rescue configuration:
aviva@router1> request system configuration rescue save
You can also save it directly from configuration mode:
aviva@router1# run request system configuration rescue save
You create a rescue configuration to define a known working configuration or a configuration with a known state that you can roll back to at any time. This alleviates having to know the rollback number when you use the rollback command. You use the rescue configuration when you need to roll back to a known configuration or as a last resort if your router configuration and the backup configuration files become damaged beyond repair. The JUNOS software does not provide a default rescue configuration.
To return to the rescue configuration, load it with the following command:
 aviva@router1# rollback rescue  aviva@router1# commit commit complete
The JUNOS software stores the rescue configuration in the /config directory:
aviva@router1> file list /config /config: juniper.conf.1.gz juniper.conf.2.gz juniper.conf.3.gz juniper.conf.gz rescue.conf.gz
To save a different configuration as the rescue configuration, just use the
request system configuration rescue save
command to overwrite the existing file. If you discover that the existing rescue configuration is not correct, but you don't have something to replace it with, delete the rescue configuration so no one
aviva@router1> request system configuration rescue delete
Recipe 1.19. Backing Up Filesystems on M-Series and T-Series Routers
You are preparing to load a different release of the JUNOS software or reload the current release and you want to save the files that are already on the router.
On M-series and T-series routers, use the following command to back up the files in the router's filesystems:
aviva@router1> request system snapshot
Before you install any JUNOS software, either upgrading,
aviva@router1> request system snapshot Copying '/' to '/altroot' .. (this may take a few minutes) Copying '/config' to '/altconfig' .. (this may take a few minutes) The following filesystems were archived: / /config
You can take a snapshot of the software at any time, but you should always do so before installing a new JUNOS software version so that you can recover to a known, stable environment in case something goes wrong when you load the software. You should also always run it after you have successfully loaded a new version of the software.
Why do you need to back up the JUNOS filesystems? One seasoned administrator has said that the less you know about the JUNOS filesystems, the more sane you will bebut still, you have to know at least a little bit. Routers have two internal storage areas, the flash drive (by default, the primary boot device) and the hard disk (the secondary boot device). A copy of the JUNOS software is stored in both. The flash drive has two filesystems (or partitions):
, which contains the active and most recent backup configurations, the rescue configuration, and software licenses, and /, which contains the JUNOS software (everything installed by the
command), the router's SSH keys, and a few other files generated from the configuration. The hard disk has one filesystem,
, which is a large partition that contains system logfiles, diagnostic dump files, archived configuration files, and
There is one additional filesystem on the router, /tmp , which is a RAM disk (a memory filesystem).
To verify that the snapshot was successful, you might want to list the contents of the filesystems (with the file list command). However, the /altroot and /altconfig filesystems are not mounted, so they are not visible even though the underlying directories are still present:
aviva@router1> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/ ad0s1a 77M 39M 32M 55% /devfs 16K 16K 0B 100% /dev/ /dev/vn0 13M 13M 0B 100% /packages/mnt/jbase /dev/vn1 37M 37M 0B 100% /packages/mnt/jkernel-7.4R1.7 /dev/vn2 12M 12M 0B 100% /packages/mnt/jpfe-M40-7.4R1.7 /dev/vn3 2.3M 2.3M 0B 100% /packages/mnt/jdocs-7.4R1.7 /dev/vn4 14M 14M 0B 100% /packages/mnt/jroute-7.4R1.7 /dev/vn5 5.1M 5.1M 0B 100% /packages/mnt/jcrypto-7.4R1.7 /dev/ad0s1e 12M 16K 11M 0% /config procfs 4.0K 4.0K 0B 100% /proc /dev/ ad1s1f 9.4G 1.2G 7.4G 14% /var
How do you know from the output of this command which partition is where?
refers to a portion of a disk. It is drive
(the storage device) slice
(the first "slice," and there's
On most M-and T-series routers, ad0 is the flash disk. In the case of router1 , an M20 router that has an RE-2.0, ad0 is the flash disk and ad1 is the hard disk:
aviva@router1> show chassis hardware detail Hardware inventory: Item Version Part number Serial number Description Chassis 25708 M20 Backplane REV 03 710-002334 BB9738 M20 Backplane Power Supply A REV 06 740-001465 005234 AC Power Supply Display REV 04 710-001519 BA4681 M20 FPM Board Routing Engine 0 REV 06 740-003239 1000224893 RE-2.0 Routing Engine 0 58000007348d9a01 RE-2.0 ad0 91 MB SanDisk SDCFB-96 i3238140903 Compact Flash ad1 11513 MB IBM-DARA-212000 AH0AHGN1017 Hard Disk Routing Engine 1 REV 06 740-003239 9000022146 RE-2.0 Routing Engine 1 d800000734745701 RE-2.0 ad0 91 MB SanDisk SDCFB-96 ggbsc410020 Compact Flash ad1 8063 MB TOSHIBA MK2016GAP Y0T39909T Hard Disk …
The output of this command also shows the manufacturer of the disks.
show system storage
command to find out the drive
aviva@router1> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 77M 40M 31M 56% / devfs 16K 16K 0B 100% /dev/ /dev/vn0 13M 13M 0B 100% /packages/mnt/jbase /dev/vn1 37M 37M 0B 100% /packages/mnt/jkernel- 7.3-20050504.0 /dev/vn2 12M 12M 0B 100% /packages/mnt/jpfe-M40- 7.3-20050504.0 /dev/vn3 2.3M 2.3M 0B 100% /packages/mnt/jdocs-7. 3-20050504.0 /dev/vn4 14M 14M 0B 100% /packages/mnt/jroute-7. 3-20050504.0 /dev/vn5 5.1M 5.1M 0B 100% /packages/mnt/jcrypto- 7.3-20050504.0 mfs:102 1.5G 12K 1.4G 0% /tmp /dev/ad0s1e 12M 24K 11M 0% /config procfs 4.0K 4.0K 0B 100% /proc /dev/ad1s1f 9.4G 2.4G 6.2G 28% /var
You see that /dev/ad0s1a is mounted at /, and you know that's the flash disk. /config is also on ad0 (the flash disk again) but on a different partition, and /var is on ad1 (the hard disk). The /dev/vn0 devices refer to the software installed on the router. All these partitions are stored on / (and /altroot ).
The show system storage command output is cluttered and contains more information than you normally care about. You can shorten by filtering out the installed software devices:
aviva@router1> show system storage except /dev/vn Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 77M 39M 32M 55% / devfs 16K 16K 0B 100% /dev/ mfs:102 1.5G 8.0K 1.4G 0% /tmp /dev/ad0s1e 12M 16K 11M 0% /config procfs 4.0K 4.0K 0B 100% /proc /dev/ad1s1f 9.4G 1013M 7.6G 11% /var
or even more:
aviva@router1> show system storage match ad /dev/ad0s1a 77M 39M 32M 55% / /dev/ad0s1e 12M 16K 11M 0% /config /dev/ad1s1f 9.4G 1013M 7.6G 11% /var
If the router boots from the hard disk or if you manually reboot from the hard disk (take a fresh snapshot first, though), you'll notice that ad0 is still the flash disk and ad1 is still the hard disk, but the root filesystem is now on the hard disk because you're running on alternate media:
aviva@router1> request system reboot media disk aviva@router1> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/ad1s1a 107M 37M 61M 38% / . . . mfs:172 1.9G 4.0K 1.8G 0% /tmp /dev/ad1s1e 12M 21K 11M 0% /config procfs 4.0K 4.0K 0B 100% /proc /dev/ad1s1f 25G 3.5G 19G 15% /var
request system reboot media disk
command takes a