Oracle Automatic Storage Manager (ASM) uses disks, and it needs to be able to identify devices and they have the correct ownership and permissions. ASMLib can be used to manage these tasks in Linux, but it is seen as an additional layer of complexity and never really gained prestige. Instead, many people use the Linux device manager "udev" to perform these tasks. This article briefly outlines the establishment of udev rules for disks using ASM in Oracle 11g. The examples all use Oracle Linux 5, 6, 7, 8, so they will conform to RHEL and CentOS 5, 6, 7 and 8.
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- background
- Determine the disk (/sbin/scsi_id)
- Make SCSI devices trust
- Create UDEV rules file
- Load update block device partition (/sbin/partprobe)
- Test rules (udevtest)
- Restart UDEV service
- Check ownership and permissions
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background
Essentially, what udev applies to the rules defined in the file "/etc/udev/rules.d" is the device node listed in the directory "/dev directory. Rules can be defined in different ways, but what we need to do is Identify the device and say what we want udev to do with it.
In this case, I know that my disk devices are named "/dev/sd? 1", "Where?" represents a simulated letter, so I can use the following rules to identify the device parameters of interest.
KERNEL=="sd?1", BUS=="scsi"