Deciding how to mount your root

This topic helps you decide whether to keep your root file system read/write or change it to read-only for execution. Table 1 describes the benefits and drawbacks of the two mount modes for the production system's root file system.

Table 1. Comparing read-only and read/write mode for the root file system of the execution system. This table compares the modes for the root file system of the execution system.
Mount mode	Benefits	Drawbacks
Read/write	You can create directories or files dynamically in the root file system. You do not have to perform the actions listed in Table 1.	Poorer performance for SYSPLEX file system operations because I/O must be directed between system images in a sysplex. Someone might modify files or directories inadvertently.
Read-only	Better performance for sysplex file system operation because I/O will not need to be directed between system images in a sysplex. No one can modify directories or files within the root file system inadvertently.	No one can create new directories or files dynamically in the root file system. You must perform the actions listed in Table 1. You have extra tasks related to leaving some directories in read/write mode such as `/dev`, `/tmp`, `/etc`, and `/var`, when these do not have their own file system separate from the root file system).

To decide whether you should leave the root file system read/write or change it to read-only, use the information in Table 1, and any other information that you might have. You should consider mounting the root file system in read-only mode, especially if you are mounting the root file system in a shared file system environment.