Integrating LVM with Hadoop and providing Elasticity to DataNode Storage
This article is about Integrating LVM with Hadoop and providing Elasticity to DataNode Storage.
I am using Rhel8 on an oracle virtual machine and I have attached two secondary harddisks to it already.
Go to the section Attaching Virtual hard disk on Virtual OS to know how to create virtual hard disk
Use the following command to know your hard Disks has been connected successfully.
Here, None of them is mounted anywhere.
First, we have to create a physical volume.
Steps to create Logical volumes :
- Create Physical volumes →
- Create a Volume group for a physical volume →
- Create a logical volume in the above-created volume group →
- Format Logical volume to mount. →
- Mount logical volume on a folder to share the storage to the Hadoop cluster →
- Update the folder name in hdfs-site.xml file in datanode →
- Take the storage from the volume group and increase the size of the logical volume on the fly. →
- Extending Volume group for more Storage →
Step 1: Create Physical volumes
Our Physical volumes for both the disk have been created successfully.
To know details of Physical volumes use the following commands
Step 2: Create a Volume group for one or more disk
vgcreate vg_name pv_name → Create Volume groumevgdisplay vg_name → To display details of volume group
Step3: Create a logical volume in the above-created volume group
lvcreate --size size_valueG --name lv_name vg_name
To display all resources we can use the following command
pvs → To list all Physical volumes
vgs → To list all Volume groups
lvs → To list all logical volumes
Step 4: Format Logical volume to mount
Step 5: Mount logical volume on a folder to share the storage to the Hadoop cluster
- create a folder to mount the logical volume
- Mount the logical volume to the folder
Step 6: Update the folder name in hdfs-site.xml file in datanode and starting datanode
hadoop-daemon.sh start datanode
jps → To check
hadoop dfsadmin -report → To cluster information
Our cluster has almost 5GB of shared storage
Step 7: Take the storage from the volume group and increase the size of the logical volume on the fly.
lvextend --size +size_noG /dev/vg_name/mylv1
Now, We have to format the increased partition to store data in it
Now, check the result.
The size of hard disk is 8 GB and if we require more storage then we can extend the Volume group
Step 8: Extending Volume group for more Storage
vgextend vg_name another_pv_name
Now, our volume group has increased to 16 GB
Now, We can extend our Logical volume.
Format and then use it.