I have a pair of 2960 tt-l switches that I wish to upgrade, adding crypto. It looks like there is not enough flash to have both images. So I will have to replace the IOS. I am on site with the switches today but cannot reboot until long after I leave the site- barring a power outage, I should be able to replace the image today and remote in late tonite and reboot and make my config changes without disrupting service correct?
Technically you are correct.
You can replace the image and login later in the day to reload, make changes and test.
Be sure to copy the existing original image to the tftp server before you delete it.
(just in case you need to go back to it)
Also, be sure to copy the existing original config to a text file and save it as well.
(just in case you encounter problems you can go back to the original config)