You can create a custom file system layout for Exadata database servers using a JSON-formatted file named fslayout.json. The file contains a list of file system mount points and corresponding sizes conforming to the following general format:

{ 
  "mount-point1": {"size": "size-value1"}[, 
  "mount-pointN": {"size": "size-valueN"}]... 
}

For example:

{
  "/": {"size": "90G"},
  "/tmp": {"size": "3G"},
  "/var": {"size": "50G"},
  "/var/log": {"size": "50G"},
  "/var/log/audit": {"size": "20G"},
  "/home": {"size": "30G"},
  "/usr": {"size": "30G"},
  "/etc": {"size": "30G"},
  "/root": {"size": "30G"},
  "/opt": {"size": "200G"},
  "/EXAVMIMAGES": {"size": "300G"},
  "/project/data": {"size": "250G"}
}

The custom file system layout defined in fslayout.json file is subject to the following requirement and restrictions:

• Each mount point (mount-pointN) must be an absolute mount path that starts with a slash character (/). The path must not contain empty path elements (no // segments). For example, /var/log is valid, but var/log and /var//log are not.

• The system canonicalizes mount paths by converting elements to lowercase (except for /EXAVMIMAGES) and removing trailing slashes (except for the single root path /). After canonicalization, duplicate mount paths are not permitted.

• The following mount paths are not permitted: /proc, /sys, /dev, /run, /srv, /sbin, /media, /lib, /lib64, /bin, /selinux, /boot, /boot/efi.

• Nested mount paths are not permitted under: /usr, /etc, /root, /opt, /EXAVMIMAGES.

• The following nested mount paths are explicitly allowed /var, /var/log, and /var/log/audit.

• Each size value (size-valueN) must be a positive number and unit suffix, either K (kilobyte), M (megabyte), or G (gigabyte).

• If you specify an entry for /EXAVMIMAGES, the minimum permitted size is 300G.

• During validation, a warning is generated if you specify a size value that is smaller than expected. If you proceed beyond the warning, the system automatically adjusts the file system size if required.