Configuring Storage Device Path Persistence Manually

You can maintain storage file path persistence by creating a rules file.

About Device Path Persistence

Understand device path persistence for Oracle Automatic Storage Management (Oracle ASM).

By default, the device file naming scheme udev dynamically creates device file names when the server is started, and assigns ownership of them to root. If udev applies default settings, then it changes Oracle device file names and owners for the disks, making the disks inaccessible when the server is restarted. For example, a voting disk on a device named /dev/sdd owned by the user grid may be on a device named /dev/sdf owned by root after restarting the server.

You must create a custom rules file. Linux vendors customize their udev configurations and use different orders for reading rules files. For example, on some Linux distributions when udev is started, it sequentially carries out rules (configuration directives) defined in rules files. These files are in the path /etc/udev/rules.d/. Rules files are read in lexical order. For example, rules in the file 10-wacom.rules are parsed and carried out before rules in the rules file 90-ib.rules.

When specifying the device information in the udev rules file, ensure that the OWNER, GROUP, and MODE are specified before all other characteristics in the order shown. For example, to include the characteristic ACTION on the UDEV line, specify ACTION after OWNER, GROUP, and MODE.

Where rules files describe the same devices, on the supported Linux kernel versions, the last file read is the one that is applied.

Configuring Device Persistence Manually for Oracle ASM

Complete these tasks to create device path persistence manually for Oracle ASM.

On existing systems (single instance or clustered), to obtain current mount paths, run the command scsi_id (/sbin/scsi_id) on storage devices on a server to obtain their unique device identifiers. When you run the command scsi_id with the -s argument, the device path and name you provide should be relative to the sysfs directory /sys (for example, /block/device) when referring to /sys/block/device.

For example, as the root user:
```
# /sbin/scsi_id -g -s /block/sdb/sdb1
360a98000686f6959684a453333524174

# /sbin/scsi_id -g -s /block/sde/sde1
360a98000686f6959684a453333524179
```
Record the unique SCSI identifiers, so you can provide them when required.

Note:
The command scsi_id should return the same device identifier value for a given device, regardless of which node the command is run from.
Configure SCSI devices as trusted devices, by editing the /etc/scsi_id.config file and adding options=-g to the file.
```
# cat > /etc/scsi_id.config
vendor="ATA",options=-p 0x80
options=-g
```
Using a text editor, create a UDEV rules file for the Oracle ASM devices, setting permissions to 0660 for the installation owner and the operating system group you have designated the OSDBA for Oracle ASM group, whose members are granted access privileges to Oracle ASM. For example, on Oracle Linux, to create a role-based configuration rules.d file where the installation owner is grid and the OSDBA group for Oracle ASM is asmdba, enter commands similar to the following:
```
# vi /etc/udev/rules.d/99-oracle-asmdevices.rules

KERNEL=="sdb1, OWNER="grid", GROUP="asmdba", MODE="0660", 
BUS=="scsi", PROGRAM=="/sbin/scsi_id", RESULT=="14f70656e66696c00000000"
KERNEL=="sdc1", OWNER="grid", GROUP="asmdba", MODE="0660",
BUS=="scsi", PROGRAM=="/sbin/scsi_id", RESULT=="14f70656e66696c00000001"
KERNEL=="sdd1", OWNER="grid", GROUP="asmdba", MODE="0660",
BUS=="scsi", PROGRAM=="/sbin/scsi_id", RESULT=="14f70656e66696c00000002"
```

On clustered systems, copy the rules.d file to all other nodes on the cluster. For example:

# sftp 99-oracle-asmdevices.rules root@node2:/etc/udev/rules.d/99-oracle-asmdevices.rules

Run the partprobe command using the syntax /sbin/partprobe devicename. For example:

# /sbin/partprobe /dev/sdc1
# /sbin/partprobe /dev/sdd1
# /sbin/partprobe /dev/sde1
# /sbin/partprobe /dev/sdf1

Run the command udevtest (/sbin/udevtest) to test the UDEV rules configuration you have created. The output should indicate that the devices are available and the rules are applied as expected. For example, for /dev/ssd1:

# udevtest /block/sdd/sdd1
main: looking at device '/block/sdd/sdd1' from subsystem 'block'
udev_rules_get_name: add symlink
'disk/by-id/scsi-360a98000686f6959684a453333524174-part1'
udev_rules_get_name: add symlink
'disk/by-path/ip-192.168.1.1:3260-iscsi-iqn.1992-08.com.netapp:sn.887085-part1'
udev_node_mknod: preserve file '/dev/.tmp-8-17', because it has correct dev_t
run_program: '/lib/udev/vol_id --export /dev/.tmp-8-17'
run_program: '/lib/udev/vol_id' returned with status 4
run_program: '/sbin/scsi_id'
run_program: '/sbin/scsi_id' (stdout) '360a98000686f6959684a453333524174'
run_program: '/sbin/scsi_id' returned with status 0
udev_rules_get_name: rule applied, 'sdd1' becomes 'data1'
udev_device_event: device '/block/sdd/sdd1' validate currently present symlinks
udev_node_add: creating device node '/dev/data1', major = '8', minor = '17', 
mode = '0640', uid = '0', gid = '500'
udev_node_add: creating symlink
'/dev/disk/by-id/scsi-360a98000686f6959684a453333524174-part1' to '../../data1'
udev_node_add: creating symlink
'/dev/disk/by-path/ip-192.168.1.1:3260-iscsi-iqn.1992-08.com.netapp:sn.84187085
-part1' to '../../data1'
main: run: 'socket:/org/kernel/udev/monitor'
main: run: '/lib/udev/udev_run_devd'
main: run: 'socket:/org/freedesktop/hal/udev_event'
main: run: '/sbin/pam_console_apply /dev/data1
/dev/disk/by-id/scsi-360a98000686f6959684a453333524174-part1
/dev/disk/by-path/ip-192.168.1.1:3260-iscsi-iqn.1992-08.com.netapp:sn.84187085-
part1'

In the example output, note that applying the rules renames OCR device /dev/sdd1 to /dev/data1.

Load the rules and restart the UDEV service. For example:
- Oracle Linux and Red Hat Enterprise Linux
```
# udevadm control --reload-rules && udevadm trigger
```
- SUSE Linux Enterprise Server
```
# /etc/init.d boot.udev restart
```

Verify that the device permissions and ownerships are set correctly.