3.1.2 Matrix Server Administration Guide

Chapter 7: Configure PSFS Filesystems 118

2. Populate the new directories with the appropriate files.

3. Create the CDSL:

ln -s /etc/{HOSTNAME} /oracle/etc

When you are logged in on serv1, the /oracle/etc symbolic link will point to

/etc/serv1.xvz.com. On serv2, it will point to /etc/serv2.xvz.com.

Matrix-Wide File Locking

Matrix Server supports matrix-wide locks on files located on PSFS

filesystems. The locks are implemented with the standard Linux flock()

system call, which is also known as the BSD flock interface.

The psfssema command-line semaphore utility provides a simple

synchronization mechanism for managing matrix-wide file locks. The

utility can be used in shell scripts on different nodes of a matrix and takes

advantage of the PSFS filesystem and its internode communication

abilities. For example, you might want to use matrix-wide file locking in a

Start or Stop script for a service or device monitor.

Create a Semaphore

To create a PSFS command-line semaphore, use this command:

$ psfssema -i <filename>

This command creates the PSFS command-line semaphore file <filename>

and the supplemental file <filename.pid> if either file does not already

exist. It then initializes the files to create the PSFS command-line

semaphore. <filename> must be a path on a PSFS filesystem.

Lock a Semaphore

To lock a PSFS command-line semaphore, use this command:

$ psfssema -g <filename>

This command locks the PSFS command-line semaphore associated with

<filename>, which is the name of a semaphore file created by psfssema -i.

If the semaphore is already locked by another node in the matrix, the

calling process blocks until the semaphore becomes available.