We all know that the UNMOUNT command removes a file system from the file system hierarchy but when we use the REMOUNT parameter with the UNMOUNT command we may be introducing confusion in some minds.

Unmounting a file system and remounting it? Makes no sense?

Well that may be so, but in fact if we look at what the REMOUNT parameter does it makes perfect sense.

In fact, the REMOUNT parameter tells the system that after the unmount is completed the system should mount the file system again but this time changing its mount mode. That is, if the file system was in READ only mode, then it should be remounted with READ/WRITE mode or if the file system was mounted with READ/WRITE mode, then it should be remounted with READ only mode.

Example 1:

File system name: SYS2.OMVS.EXAMPLE

Mount mode: RDWR (Read/Write mode)

When we issue the command UNMOUNT FILESYSTEM(SYS2.OMVS.EXAMPLE) REMOUNT we tell the system that we wish to change the mount mode of the file system to READ only mode. The system then unmounts the file system and remounts it with READ only mode.

Example 2:

File system name: SYS2.OMVS.EXAMPLE

Mount mode: READ

When we issue the command UNMOUNT FILESYSTEM(SYS2.OMVS.EXAMPLE) REMOUNT we tell the system that we wish to change the mount mode of the file system to READ/WRITE (RDWR) mode. The system then unmounts the file system and remounts it with READ/WRITE mode.