Question-54: Select correct statements with regards to Cloudera Operating System Filesystems for Logical Volume Manager.

Question-54: Select correct statements with regards to Cloudera Operating System Filesystems for Logical Volume Manager.

1. Logical Volume Manager (LVM) should not be used for data drives.
2. Logical Volume Manager (LVM) should be used for data drives.
3. Logical Volume Manager (LVM) should not be used for OS drives.
4. Logical Volume Manager (LVM) should be used for OS drives.
5. You should use an extent-based file system.

Answer:

Exp: In Linux there are several choices for formatting and organizing drives. That being said, only a few choices are optimal for Hadoop.

In RHEL/CentOS, the Logical Volume Manager (LVM) should not be used for data drives. It is not optimal and can lead to combining multiple drives into one logical disk, which is in complete contrast to how Hadoop manages fault tolerance across HDFS. It is beneficial to keep LVM enabled on the OS drives. Any performance impact that may occur is countered by the improvement to manageability of the system. Using LVM on the OS drives enables the admin to avoid over-allocating space on partitions. Space needs can change over time and the ability to dynamically grow a file system is better than having to rebuild a system. Do not use LVM to stripe or span logical volumes across multiple physical volumes to mimic RAID.

Cloudera recommends using an extent-based file system. This includes ext3, ext4, and xfs. Most new Hadoop clusters use the ext4 filesystem by default. Red Hat Enterprise Linux 7 uses xfs as its default filesystem.