Linux (centos) install EMCPower multipath

PowerPath is a host-based software for intelligently managing multipath I/O. PowerPath can achieve multipathing, automatic failover, and dynamic load balancing, and can be used to manage Symmetrix, Clariion, and third-party storage arrays.

This article mainly introduces the function of EMC multipath control software PowerPath.

What is PowerPath:

PowerPath is a host-based software for intelligently managing multipath I/O. PowerPath can achieve multipathing, automatic failover, and dynamic load balancing, and can be used to manage Symmetrix, Clariion, and third-party storage arrays.

Path refers to the physical route between the host and the logical unit (LU) of the storage system. Including host bus adapter (HBA) ports, cables, swithes, storage system interfaces and ports, and LU. LU refers to a physical or virtual device that can be addressed as a single storage volume. For the iSCSI standard, the path refers to the Initiator-Target-LUN.

PowerPath supports a multi-path connection to a logical device. Using PowerPath can provide the following functions:

Automatic failover when a hardware failure occurs. PowerPath automatically detects the path failure and I / O redirection to another one path.

Dynamic multi-path load balancing. PowerPath distributes I/O requests to a logical device across all available paths, so it improves I/O performance and reduces management time, and reduces downtime due to the need to statically configure paths between logical devices.

Multipath function:

PowerPath can connect to logical devices through multiple ports. Users can use two or more interfaces to configure logical devices as shared devices. In this way, all logical devices are visible on all ports, thereby improving availability.

As shown in the figure below, without PowerPath, the host’s SCSI driver will not be able to connect to a logical device through multipath. This is because most operating systems treat a path as a unique logical device, even if multiple paths are connected to the same logical device. This will result in the loss of data when the system crashes. PowerPath eliminates such restrictions.

When using PowerPath, users can connect to the logical device through multiple paths to share the host and storage ports. The number of shared paths configured with Fabric will be greater. For example, the host has 4 HBAs connected to 100 logical devices on 4 ports of the host through Fabric, and PowerPath manages 1600 paths. (4HBAs X 4Fas x 100 logical devices = 1600).

As shown in the figure above, both logical devices can be accessed through the two interface ports, so that the I/O of the logical device can be shunted on multiple paths. In the figure above, the two paths are connected to logical device 0 and the two are connected to logical device 1.

PowerPath takes advantage of the multi-path performance of the storage system to provide load balancing or anti-path failure functions between the host and logical devices. Thus PowerPath can:

Increase I/O throughput by sending I/O requests to the same logical device on multiple paths.

Prevent data loss by redirecting I/O requests from one failed path to another working path.

Install EMCPower multipath software on Linux(centos)

Details

System: centos 6.x
software: EMCPower.LINUX.6.1.0.b091.tar.gz
software download:

installation method

(1) Upload the multi-path software installation package to the /tmp directory
EMCPower.LINUX-6.0.1.00.00–043.RHEL6.x86_64.rpm
shell>tar -xf EMCPower.LINUX.6.1.0.b091.tar.gz

(2) rpm install
shell>rpm -ivh EMCPower.LINUX-6.1.0.00.00–091.OL6.x86_64.rpm
Note: shell>echo $? returns 0 correct, also see the output information

(3) Register the license for multi-path software (provided by the original manufacturer)
shell> emcpreg -add key xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xxxx

(4) Verify the license is successful
shell> emcpreg -list

(5) Check the powerpath service
shell>service powerpath status
powerpath: unrecognized service

(6) View process
shell>ps -ef |grep emc
shell>ps -ef |grep power

Note: There may be no process
(7) Check the multipath port status
shell>powermt display ports
ERROR: Cannot open PowerPath. Initialization error

(8) After completing the above view, if the power path is not up, you need to restart the system
shell>reboot
after restarting, then look at the process and service

(9) Check the disk party status after restart
shell>powermt display dev=all

(10) After installing multipath, check the gathering disk
shell>ls -l /dev/emcpower*

Thanks for reading this post.