.备份上传资料，镜像（tftp工具） 2.指定IOS镜像 sas5520(config)#boot system flash/asa917-25-k8.bin 出现以下信息： INFO: Converting flash/asa917-25-k8.bin to disk0:/flash/asa917-25-k8.bin WARNING: BOOT variable added, but unable to find disk0:/flash/asa917