Prerequisite for virtual machines that run on the Linux operating system

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When a logical partition runs on the Linux operating system (SUSE or Ubuntu Linux distributions), the Linux operating system uses the Small Computer System Interface (SCSI) ID as the device ID for some file systems during installation. However, the SCSI ID might change when you recover the virtual machine from the active site to the backup site. In this case, the virtual machine cannot start in the backup site because of the change in SCSI ID. Therefore, you must replace the SCSI ID with the Universal Unique Identifier (UUID) in the /etc/fstab file and the Boot loader option after you install the Linux operating system in the virtual machine.

To replace the SCSI ID with UUID in the Linux virtual machine after installing the operating system, complete the following steps:

  1. Identify the UUID of the required disk by running the following commands:
    1. Identify the disk that contains the Linux operating system by running the following command:
      linux:/usr/bin # fdisk -l
      An output that is similar to the following example is displayed:
      Disk /dev/sda: 107.4 GB, 107375493120 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 209717760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbac70600

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048        2854         403+  41  PPC PReP Boot
/dev/sda2          417792     4626431     2104320   82  Linux swap / Solaris
/dev/sda3         4626432   209717247   102545408   83  Linux

Disk /dev/sdb: 107.4 GB, 107375493120 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 209717760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbac70600

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048        2854         403+  41  PPC PReP Boot
/dev/sdb2          417792     4626431     2104320   82  Linux swap / Solaris
/dev/sdb3         4626432   209717247   102545408   83  Linux

Disk /dev/mapper/360000970000196800508533033323741: 107.4 GB, 107375493120 bytes
255 heads, 63 sectors/track, 13054 cylinders, total 209717760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xbac70600

                                         Device Boot      Start         End      Blocks   Id  System
/dev/mapper/360000970000196800508533033323741_part1   *        2048        2854         403+  41  PPC PReP Boot
/dev/mapper/360000970000196800508533033323741_part2          417792     4626431     2104320   82  Linux swap / Solaris
/dev/mapper/360000970000196800508533033323741_part3         4626432   209717247   102545408   83  Linux
      In this example, the /dev/sda3 boot device is the disk that contains the Linux operating system.
    2. List the corresponding UUID of the disks by running the following command:
      linux:/dev/disk/by-id # blkid
      An output that is similar to the following example is displayed:
      /dev/sda2: UUID="2d6e8edb-cc0e-4db1-9125-7d4ec8faf58d" TYPE="swap"
/dev/sda3: UUID="6187ca4a-1589-4f57-8c3e-33a4043450b8" TYPE="ext3"
/dev/sdb2: UUID="2d6e8edb-cc0e-4db1-9125-7d4ec8faf58d" TYPE="swap"
/dev/sdb3: UUID="6187ca4a-1589-4f57-8c3e-33a4043450b8" TYPE="ext3"
/dev/mapper/360000970000196800508533033323741_part2: UUID="2d6e8edb-cc0e-4db1-9125-7d4ec8faf58d" TYPE="swap"
      In this example, you can identify the UUID of the /dev/sdb3 disk.
  2. Open and edit the /etc/fstab file to replace the SCSI ID of the disk with the UUID of the disk. For example:
    linux:~ # cat /etc/fstab
/dev/mapper/360000970000196800508533033323741_part2 swap                 swap       defaults
        0 0
#/dev/disk/by-id/scsi-360000970000196800508533033323741-part3 /          ext3       acl,user_xattr
        1 1
/dev/disk/by-uuid/6187ca4a-1589-4f57-8c3e-33a4043450b8 /boot             ext3       acl,user_xattr
        1 1  ====> Replace SCSI ID with UUID 
proc                 /proc                proc       defaults              0 0
sysfs                /sys                 sysfs      noauto                0 0
debugfs              /sys/kernel/debug    debugfs    noauto                0 0
devpts               /dev/pts             devpts     mode=0620,gid=5       0 0
  3. Change the Boot loader option in the Linux virtual machine by using the Linux operating system setup and configuration tool, YaST. Go to YaST > System > Boot loader. Edit the root device and replace the SCSI ID with the UUID of the disk.