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Formatting and Mounting Bricks

Formatting and Mounting Bricks

Creating a Thinly Provisioned Logical Volume

To create a thinly provisioned logical volume, proceed with the following steps:

  1. Create a physical volume(PV) by using the pvcreate command. For example:

    pvcreate --dataalignment 128K /dev/sdb
    

    Here, /dev/sdb is a storage device. Use the correct dataalignment option based on your device.

    Note: The device name and the alignment value will vary based on the device you are using.

  2. Create a Volume Group (VG) from the PV using the vgcreate command: For example:

    vgcreate --physicalextentsize 128K gfs_vg /dev/sdb
    

    It is recommended that only one VG must be created from one storage device.

  3. Create a thin-pool using the following commands:

    1. Create an LV to serve as the metadata device using the following command:

      lvcreate -L metadev_sz --name metadata_device_name VOLGROUP
      

      For example:

      lvcreate -L 16776960K --name gfs_pool_meta gfs_vg
      
    2. Create an LV to serve as the data device using the following command:

      lvcreate -L datadev_sz --name thin_pool VOLGROUP`
      

      For example:

      lvcreate -L 536870400K --name gfs_pool gfs_vg
      
    3. Create a thin pool from the data LV and the metadata LV using the following command:

      lvconvert --chunksize STRIPE_WIDTH --thinpool VOLGROUP/thin_pool --poolmetadata VOLGROUP/metadata_device_name
      

      For example:

      lvconvert --chunksize 1280K --thinpool gfs_vg/gfs_pool --poolmetadata gfs_vg/gfs_pool_meta
      

      Note: By default, the newly provisioned chunks in a thin pool are zeroed to prevent data leaking between different block devices.

      lvchange --zero n VOLGROUP/thin_pool
      

      For example:

      lvchange --zero n gfs_vg/gfs_pool
      
  4. Create a thinly provisioned volume from the previously created pool using the lvcreate command:

    For example:

    lvcreate -V 1G -T gfs_vg/gfs_pool -n gfs_lv
    

    It is recommended that only one LV should be created in a thin pool.

    Format bricks using the supported XFS configuration, mount the bricks, and verify the bricks are mounted correctly.

    Run mkfs.xfs -f -i size=512 -n size=8192 -d su=128k,sw=10 DEVICE to format the bricks to the supported XFS file system format. Here, DEVICE is the thin LV(here /dev/gfs_vg/gfs_lv). The inode size is set to 512 bytes to accommodate for the extended attributes used by GlusterFS.

    Run mkdir /mountpoint to create a directory to link the brick to.

    Add an entry in /etc/fstab:

    /dev/gfs_vg/gfs_lv    /mountpoint  xfs rw,inode64,noatime,nouuid      1 2
    

    Run mount /mountpoint to mount the brick.

    Run the df -h command to verify the brick is successfully mounted:

    # df -h
    /dev/gfs_vg/gfs_lv   16G  1.2G   15G   7% /exp1
    
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