Mastering UNIX® Shell Scripting: Bash, Bourne, and Korn Shell Scripting for Programmers, System Administrators, and UNIX Gurus, Second Edition

CHAPTER20

Monitoring for Stale Disk Partitions (AIX-Specific)

Monitoring for stale disk partitions is an AIX thing. To understand this chapter you need to be familiar with the Logical Volume Manager (LVM) that is at the heart of the AIX disk subsystem. We will get to the LVM in the next section. At the high level a stale disk partition means that the mirrored disks are not in sync. Sometimes when you find stale disk partitions you can resync the mirrors, and all is well. If the mirrors will not sync up, you may be seeing the first signs of a failing disk.

We are going to look at three methods of monitoring for stale partitions:

• Monitoring at the logical volume (LV) level
• Monitoring at the physical volume (PV), or disk, level
• Monitoring at the volume group (VG), PV, and LV levels to get the full picture

All three methods will report the number of stale disk partitions, but it is nice to know the VG, PV, and the LV that are involved in the unsynced mirrors. We are going to step through the entire process of building these shell scripts, starting with the command syntax required to query the system. Before we start our scripting effort, I want to give you a high-level overview of the AIX LVM and the commands we are going to use.

AIX Logical Volume Manager (LVM)

Unlike most UNIX operating systems, IBM manages disk resources with what IBM calls the Logical Volume Manager (LVM). The LVM consists of the following components, starting with the smallest.

Starting at the physical volume ...