Using udev to Simplify HP Serviceguard for Linux Configuration, October 2006

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Using udev to Simplify HP Serviceguard for Linux

Configuration

October 2006

Executive Summary...................................................................... 2

Introduction ................................................................................ 2

Audience ................................................................................. 2

Naming Considerations ............................................................... 3

CCISS ..................................................................................... 3

Special Naming for LockLUN........................................................ 4

Configuring udev ........................................................................ 4

Creating udev Entries ................................................................ 4

Creating Rules for a Device........................................................ 5

Creating Links for Persistence...................................................... 6

Summary of content (7 pages)

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Using udev to Simplify HP Serviceguard for Linux Configuration October 2006 Executive Summary...................................................................... 2 Introduction ................................................................................ 2 Audience ................................................................................. 2 Naming Considerations ............................................................... 3 CCISS ..............................................................
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Executive Summary Device names are generally assigned by Linux at boot time. Using these device names in scripts or other applications can cause problems as configurations change over time. HP Serviceguard for Linux requires the use of device names in user modified scripts and for LockLUN. This white paper describes the use of the Linux function udev to provide persistent device names with Serviceguard for Linux so that scripts are not affected by changes in system configuration.
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Naming Considerations To better understand when to use persistent naming, it is useful to know what functions can have problems if device names change. Three potential problem areas with Serviceguard for Linux are: • • • LockLUN cmresserviced LVM When configuring a LockLUN with Serviceguard, a LUN name must be given. Typically, the LUN name is based on the device name. This is then built into the Serviceguard configuration.
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Special Naming for LockLUN Serviceguard for Linux treats the LockLUN device in a special way. This places a restriction on the types of device names that are acceptable. Only names starting with /dev/sd or /dev/cciss are accepted for LockLUN. When using udev, the recommended persistent names for LockLUN are /dev/sdLockLUN since CCISS devices are not supported. Partition numbers will be added by the system. Configuring udev The configuration files for udev are in /etc/udev/rules.d.
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Console output: Welcome to the Linux Lun Migration and Lun Persistence installer Version 1.1 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ 1. Lun Migration with Lun Persistency ~ ~ 2. Lun Persistency Only (2.4 Linux Kernel) ~ ~ 3. Lun Persistency Only (2.6 Linux Kernel) ~ ~ 4. Exit ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Enter your Choice (1/2/3/4): 3 Installing Lun Persistence utility (hpudev-cfg)for 2.6 Kernel Please Wait... Preparing...
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2. Edit the /etc/udev/rules.d/10-HP-Local.rules file by appending the output of step 1 at the end of the file. Each rule should be entered as a single line. To have the partitions represented, add “%n” to the SYMLINK string: SYMLINK="hpdev/mylink-sda%n” NOTE: If you add the line by redirecting the output of hp_gen_rule to 10-HP-Local.rules you must edit that file and delete the line that has the “Note:” and all blank lines that were added.
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