which files are cleanup candidates?

When upgrading the Junos OS, you reference the image name and a local path or a remote server within a URI. You should store
the Junos OS images copied to a device running the Junos OS in preparation for an upgrade in the /var/tmp directory. You can
delete Junos images stored in the /var/tmp directory when you perform the file system cleanup operation using the request
system storage cleanup CLI command. To determine which files are cleanup candidates, you can issue the request
system storage cleanup dry-run command.
Although plenty of storage space typically exists, it is a good practice to check available storage capacity before downloading a
new Junos OS image. You can view compact-flash device storage details with the CLI show system storage command.
As the graphic indicates, when an upgrade is performed, the system must be rebooted for the new Release to take affect. To
save time and keystrokes, you can use the reboot option when performing the upgrade. Once the Junos OS is installed, you
are notified that the system is rebooting. To complete the installation, use the console connection to view details of the upgrade
process. Watch for any error messages indicating a problem with the upgrade. Once the system has rebooted, you can issue the
show version command, illustrated earlier in this chapter, to verify the Junos OS Release. You can also review the boot
messages by issuing the show system boot-messages command.