新建的虛擬機，想搭建一個yum，於是乎就先進行了一次本地掛載。
結果竟然掛載不上。
[root@localhost ~]# mount /root/rhel-server-6.5-x86_64-dvd.iso /mnt/
mount: /root/rhel-server-6.5-x86_64-dvd.iso is not a block device (maybe try `-o loop'?)
經過解決，發現mount後需要加-o loop
-o loop=：使用 loop 模式用來將一個檔案當成硬盤分割掛上系統
網上有人說，iso文件鏡像都是需要添加-o loop.
[root@localhost ~]# mount -o loop /root/rhel-server-6.5-x86_64-dvd.iso /mnt/
[root@localhost ~]# ls /mnt/
.discinfo media.repo RELEASE-NOTES-or-IN.html
EFI/ Packages/ RELEASE-NOTES-pa-IN.html
EULA README RELEASE-NOTES-pt-BR.html
EULA_de RELEASE-NOTES-as-IN.html RELEASE-NOTES-ru-RU.html
EULA_en RELEASE-NOTES-bn-IN.html RELEASE-NOTES-si-LK.html
EULA_es RELEASE-NOTES-de-DE.html RELEASE-NOTES-ta-IN.html
EULA_fr RELEASE-NOTES-en-US.html RELEASE-NOTES-te-IN.html
EULA_it RELEASE-NOTES-es-ES.html RELEASE-NOTES-zh-CN.html
EULA_ja RELEASE-NOTES-fr-FR.html RELEASE-NOTES-zh-TW.html
EULA_ko RELEASE-NOTES-gu-IN.html repodata/
EULA_pt RELEASE-NOTES-hi-IN.html ResilientStorage/
EULA_zh RELEASE-NOTES-it-IT.html RPM-GPG-KEY-redhat-beta
GPL RELEASE-NOTES-ja-JP.html RPM-GPG-KEY-redhat-release
HighAvailability/ RELEASE-NOTES-kn-IN.html ScalableFileSystem/
images/ RELEASE-NOTES-ko-KR.html Server/
isolinux/ RELEASE-NOTES-ml-IN.html TRANS.TBL
LoadBalancer/ RELEASE-NOTES-mr-IN.html .treeinfo
之後掛載成功！