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See Also<br />

Recipe 1.17<br />

1.19 Backing Up Filesystems on M-Series and T-Series<br />

Routers<br />

Problem<br />

You are preparing to load a different release of the JUNOS software or reload the<br />

current release and you want to save the files that are already on the router.<br />

Solution<br />

On M-series and T-series routers, use the following command to back up the files in<br />

the router’s filesystems:<br />

aviva@router1> request system snapshot<br />

<strong>Discussion</strong><br />

Before you install any JUNOS software, either upgrading, downgrading, or reinstalling<br />

the current software version, you should always back up the files in the router’s<br />

filesystem. This operation is sometimes called taking a snapshot of the software. The<br />

request system snapshot command copies the files and filesystems from the current<br />

running active partitions to standby partitions. Specifically, it copies the / (root) filesystem<br />

to /altroot, and the /config filesystem to /altconfig. You see information about<br />

the copying as the command is running:<br />

aviva@router1> request system snapshot<br />

Copying '/' to '/altroot' .. (this may take a few minutes)<br />

Copying '/config' to '/altconfig' .. (this may take a few minutes)<br />

The following filesystems were archived: / /config<br />

You can take a snapshot of the software at any time, but you should always do so<br />

before installing a new JUNOS software version so that you can recover to a known,<br />

stable environment in case something goes wrong when you load the software. You<br />

should also always run it after you have successfully loaded a new version of the<br />

software.<br />

Why do you need to back up the JUNOS filesystems? One seasoned administrator<br />

has said that the less you know about the JUNOS filesystems, the more sane you will<br />

be—but still, you have to know at least a little bit. Routers have two internal storage<br />

areas, the flash drive (by default, the primary boot device) and the hard disk (the secondary<br />

boot device). A copy of the JUNOS software is stored in both. The flash drive<br />

has two filesystems (or partitions): /config, which contains the active and most recent<br />

backup configurations, the rescue configuration, and software licenses, and /, which<br />

Backing Up Filesystems on M-Series and T-Series Routers | 43<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.

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