Tag Archives: redhat

Expand Logical Volume in Red Hat VMware

After adding a separate disk run to verify if the space was added:

  1. fdisk -l
  2. create a new partition fdisk /dev/sdb
    1. p – to print current partition table
    2. n – to create a new partition
    3. p – for primary
    4. 1 – depending on the output of the partition table output
    5. press return two times to accept the defaults (first and last sector)
    6. t – to change the system’s partition ID
    7. 8e – to change to Linux LVM
    8. w – to write the changes
  3. restart VM
  4. fdisk -l – to verify that partition was successfully created
  5. convert a partition to physical volume
    $ pvcreate /dev/sdb1
    Physical volume “/dev/sdb1” successfully created
  6. Extend current volume group
    vgextend rhel /dev/sdb1
    Volume group “rhel” successfully extended
  7. Run vgdisplay to verify if free space was added
    vgdisplay rhel | grep “Free”
    Free  PE / Size       4095 / 16.00 GiB
  8. extend logical volume with free space
    lvextend -l +100%FREE /dev/rhel/root
    Extending logical volume root to 66.00 GiB
    Logical volume root successfully resized
  9. Expand ext3 file system online inside of Logical Volume
    xfs_growfs /dev/rhel/root – Red Hat 7
    ext2online /dev/rhel/root
    resize2fs /dev/rhel/root
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kernel panic – not syncing: VFS: unable to mount root fs on unknown-block(0,0)

This error has been thrown while upgrading from Red Hat 6.3 Santiago to Red Hat 6.5
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
Pid: 1, comm: swapper Not tainted 2.6.32-431.17.1.el6.i686 #1
Call Trace:
[] ? panic+0x6e/0x122
[] ? mount_block_root+0x1dd/0x274
[] ? prepare_namespace+0x14b/0x191
[] ? sys_access+0x1f/0x30
[] ? kernel_init+0x226/0x234
[] ? kernel_init+0x0/0x234
[] ? kernel_thread_helper+0x7/0x10

The error was most probably caused by some kernel bug (see references).

SOLUTION:
dracut

  1. Navigate to /boot/ directory
  2. Run the command to recreate an initial RAM disk image:
    dracut "initramfs-$(uname -r).img" $(uname -r)
  3. Reboot the machine

References:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/sec-Verifying_the_Initial_RAM_Disk_Image.html