Junos OS

Hi everybody.

request system snapshot

Does the command  also copy  Start-up config to hard drive besides JUNOS?

Much appreciated!!

Hi sarahr202,

It does copy the configuration on the device as well besides the JUNOS.

As mentioned in below link;

https://www.juniper.net/documentation/en_US/junos/topics/reference/command-summary/request-system-snapshot.html

• On the router, back up the currently running and active file system partitions to standby partitions that are not running. Specifically, the root file system (/) is backed up to /altroot, and /config is backed up to /altconfig. The root and /config file systems are on the router's flash drive, and the /altroot and /altconfig file systems are on the router's hard drive.
• On the switch, take a snapshot of the files currently used to run the switch—the complete contents of the root (/) , /altroot, /config, /var, and /var-tmp directories, which include the running Junos OS, the active configuration, and log files.

Thanks again

Hi,

Yes, it copies the config also. Specifically, the root file system (/) is backed up to /altroot, and /config is backed up to /altconfig.

In a macro view, request system snapshot copies everything from the primary boot device to the secondary boot device ( usually Hard Disk) required to boot the routing engine.
This command creates a snapshot of primary boot device on secondary.


This is critical when the primary boot device (Compact flash) fails to boot, the router boots from the secondary boot device without any issue if snapshot is performed.

This command is recommended after any Junos upgrade to sync the secondary boot device.

There could be a case when you upgraded from Junos 10 to 14 and after a few days of upgrade the compact flash fails to boot.
if the request system snapshot was not performed after the upgrade, the secondary boot device will boot from the previous snapshot i.e Junos 10 instead of 14.


Below link can be referred for more details:

https://www.juniper.net/documentation/en_US/junos/topics/reference/command-summary/request-system-snapshot.html

Regards,

Rahul

Please mark my solution as accepted if it helped

Hi Rahul,

Just thought about it:

If we run this command  request system snapshot multiple times, will it create multiple files in /altconfig/ /altroot/ or files are simply overwiriiten?

If it indeed creates multiple files above, then how does router determine which JUNOS to boot, which CONFIG to load?

Thanks and have a nice day!!

Hi,

The request system snapshot will overwrite the previous snapshot and the latest snapshot will be used by the secondary boot device if primary fails.

Regards,

Rahul

Please mark my solution as accepted if it helped.

Thanks Rahul