In order to export /usr and /bin via NFSv4, /exports was created and contains working bind mounts to /usr and /bin. The following lines are added to /etc/exports on the NFS server:



/exports      192.0.1.0/24(rw,sync,fsid=0,crossmnt,no_subtree_check)
/exports/usr  192.0.2.0/24(rw,sync,fsid=0,crossmnt,no_subtree_check)
/exports/bin  192.0.2.0/24(rw,sync,fsid=0,crossmnt,no_subtree_check)

After running

mount -t nfs server:/ /mnt

of an NFS-Client, it is observed that /mnt contains the content of the server's /usr directory instead of the content of the NFSv4 root folder.

Which option in /etc/exports has to be changed or removed in order to make the NFSv4 root folder appear when mounting the highest level of the server? (Specify ONLY the option name without any values or parameters.)

Answer: fsid

題解

「fsid」可以設定每個NFS的ID，大部分的情況下不需要自己設定ID。「0」或是「root」表示分享目錄的根目錄的ID，也就是說可以藉由設定「fsid=0」或是「fsid=root」，來讓某個目錄變成是NFS的根目錄。

此題的「fsid=0」用法很怪，導致「/exports/usr」變成是NFS的根目錄，應該要移除掉。