Preparing RHEL LUNs with mount points using DMMP alias names for transition using the CLI

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Before transition of a mount point using a DMMP device name, you must replace the DMMP device name with its respective file system UUID number.

This procedure applies to copy-based transitions and copy-free transitions.

Steps
  1. Identify and record the SCSI device ID for the LUN to be transitioned:

    sanlun lun show

    The SCSI device ID is listed under the filename column in the output.

  2. Identify and record the DMMP device name for the LUN to be transitioned:

    multipath -ll SCSI_device_ID

    In the following example, 360a9800037534562572b453855496b41 is the DMMP device name:

    [root@IBMx3550M3-229-169 ~]# multipath -ll /dev/sdc
    dmmp_fs_lun (360a9800037534562572b453855496b41) dm-3 NETAPP, LUN
    [size=1.0G] [features=3 queue_if_no_path pg_init_retries 50] [hwhandler=0][rw]
    \_ round-robin 0 [prio=2][active]
    	\_ 9:0:0:1 sdc 8:32  [active][ready]
    	\_ 9:0:0:1 sdg 8:96  [active][ready]
  3. Identify the file system configured on the DMMP device:

    blkid | grep -i DMMP_device_name

    The TYPE value in the output identifies the file system.

    In the following example, the file system is ext3.

    [root@ibmx3550-229-108 ~]#blkid | grep -i 3600a09804d532d79565d47617679658
    /dev/mapper/3600a09804d532d79565d47617679658:
    UUID="450b999a-4f51-4828-8139-29b20d2f8708" TYPE="ext3" SEC_TYPE="ext2"
  4. Identify the UUID number for the LUN:

    dumpe2fs device_path_name | grep UUID

  5. Identify the directory on which the DMMP device is mounted:

    df -h

    In the following example, /mnt/dmmp_ext3 represents the directory on which the DMMP device is mounted:

    [root@IBMx3550M3-229-169 ~]# df -h
    Filesystem Size Used Avail Use% Mounted on
    /dev/mapper/dmmp_fs_lun
    1008M 34M 924M 4% /mnt/dmnp_ext3
  6. Verify in the /etc/fstab file that the mount points for the DMMP device are defined:

    cat /etc/fstab

    The DMMP device name and mount directory should be displayed in the output.

  7. Create a backup of the /etc/fstab file:

    cp /etc/fstab /etc/fstab_pre_transition_bkup

  8. Edit the /etc/fstab file to replace the DMMP device name with its respective file system UUID number.