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Setting up multipathing

To set up multipath for Linux, you need to complete a few steps.

Steps

  1. After the host reboots, the multipath daemon should be running as seen in the following example:
    root@lnx197-123 ~]# ps -ef | grep multipathd
    root      5713     1  0 22:44 ?        00:00:00 /sbin/multipathd
    root      5739  1783  0 22:44 pts/1    00:00:00 grep multipathd
    If the multipath daemon is not running, ensure that it runs after the reboot. You can start the multipath daemon by running the following command:
    [root@lnx197-123 ~]# chkconfig --level 345 multipathd on
    Note: SnapDrive for UNIX does not support the use of user-friendly names or aliases in multipath environments. Ensure that the user_friendly_names=no parameter is set and that there are no aliases defined in the /etc/multipath.conf file.
    • You do not have to set any values in the /etc/multipath.conf file if you are using either Red Hat Enterprise Linux (RHEL) 6.4 or later or Oracle Linux 6.4 or later. However, you must still maintain a dummy /etc/multipath.conf file, which can either be empty or contain the blacklisting info, if required.
    • You do not have to maintain a /etc/multipath.conf file if you are using SUSE Linux Enterprise Server (SLES) 11 SP3 or later. However, you can have a /etc/multipath.conf file to contain the blacklisting info, if required.
  2. Replace the string HITACHI_HUS103073FL3800_V3WTL7XA with the output of the command scsi_id -gus /block/<LD>, where LD is the local block device name.
    Note: For some local block devices, the scsi_id command may not return any strings. In that case, the local block device needs to be blacklisted by using devnode directive.
  3. Increase the number of open file descriptors that a process can open in the host by appending the following lines in the /etc/security/limits.conf file:
    soft nofile 4096 
           hard nofile 4096
  4. Ensure that the Linux SG Driver is always loaded after the system reboot by entering the following command:
    echo "modprobe sg" >> /etc/rc.local
  5. Reboot the host to ensure that settings are active.
    Note: The lvm2-2.02.17-7.27.8 and the filter setting must be assigned as = ["r|/dev/.*/by-path/.*|", "r|/dev/.*/by-id/.*|", "r|/dev/cciss/.*|", "a/.*/"] in the lvm.conf file in SLES10 SP2.