Implementation of MultiPath software in Linux

Source: Internet
Author: User

Implementation of MultiPath software in Linux

How Multipath works

When the multipath is started, it uses the system command scsi_id-eg-s/block/sdX to obtain the UUID (universally unique identify) of all block devices in proc/partitions ), then, all Block devices with the same UUID are grouped into a Group to generate a corresponding independent device in/dev/mapper. After the device is generated, you can use fdisk or parted to partition the partition. You can use the kpartx command to register the partition, and then use the system command to create the file system and mount.

Generally, the device-mapper software package is installed simultaneously during the installation of the series. Run the linux command rpm to check whether the software package has been installed. Run the command rpm-ivh to install the following rpm package:

Device-mapper -*

Device-mapper-multipath -*

Device-mapper-1 *

Start and configure multiple paths

Start multi-path and use the mpathconf command to create a default template. Create a default configuration to start and activate the multipathd process. Run the following command:

Mpathconf -- enable -- with_multipathd y

We recommend that you restart the multi-path software after the configuration is complete:

/Etc/init. d/multipathd restart

Note: multipath is generated under/etc/after startup. the conf file and bindings and wwid are generated under/etc/multipath. The wwid records the unique IDs of all mounted disks in the system, bindings records the mapped disk corresponding to the ID. After binding, files such as mpathx will be generated under/dev/mapper.

Remarks ------------------------------------------------------

If no data is generated, you can follow Deploying Oracle RAC 11g R2 Database on Red Hat elastic iselinux 6

As follows:

1. As the root user, install the device-mapper-multipath package using the yum package

Manager.

# Yum install device-mapper-multipath

2. Copy the multipath. conf file found within/usr/share/doc/device-mapper-multipath-0.4.9/

To/etc/

# Cp/usr/share/doc/device-mapper-multipath-0.4.9/multipath. conf/etc/

3. Capture the scsi id of the local disk (s) on the system.

# Scsi_id -- whitelisted -- replace-whitespace -- device =/dev/sda

3600508b1001030353434363646301200

4. Uncomment and modify the blacklist section within the/etc/multipath. conf file to include

The scsi id of the local disk on the system. Once complete, save the changes made

The multipath. conf file.

Blacklist {

Wwid 3600508b1001030353434363646301200

Devnode "^ (ram | raw | loop | fd | md | dm-| sr | scd | st) [0-9] *"

Devnode "^ hd [a-z]"

}

5. Start the multipath daemon.

# Service multipathd start

Starting multipathd daemon: [OK]

6. Enable the multipath daemon to ensure it is started upon boot time.

# Chkconfig multipathd on

7. Identify the dm-device, size, and WWID of each device mapper volume for Oracle

OCR and voting disks, data disks and recovery disks. In this example, volume mpathb

Is identified via the following command:

# Multipath-ll

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