The warm reload feature of the Cisco IOS was offered in IOS version 12.3(2)T.
How to perform a warm upgrade in the Cisco IOS
Use the reload warm file command, like this:
Router# reload warm file tftp://1.1.1.1/c2800nm-advipservicesk9-mz.124-15.T5.bin
This command actually has a number of options such as scheduling and creating a comment:
reload [/verify | /noverify] [warm [file url]] [in [hh:]mm | at hh:mm [month day | day month
The job of the warm reload feature is to allow you to reload your routers without having to read the IOS image from flash.
How do you use warm reload in the Cisco IOS?
The job of the warm reload feature is to allow you to reload your routers without having to read the IOS image from flash.
You can configure the warm reboot functionality with the warm reboot global command, like this:
Router(config)# warm-reboot 10 uptime 10
This enables the router to reboot a maximum number of 10 times using the warm reboot function and ensures that the router will sit for no more than 10 minutes after an attempted warm reload that doesn’t result in a successful boot. Next, you must do one clean, cold reload of the router. After that, you can use the reload warm command to quickly reboot your router.
You can also use show warm-reboot to find the statistics concerning how many warm reloads have happened and how much space is taken up by warm reload storage.