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Migrate/Transfer/Copy AWS Data from volumes or S3 to Hadoop

Hadoop distcp s3n://bucketname/directoryname/test.csv /user/myuser/mydirectory/

 

Detail information can be found at following link.

https://hortonworks.github.io/hdp-aws/s3-copy-data/index.html

Placing Namenode in safemode and Perform checkpoint

Normally in real environment secondary node performs checkpoint operation and keep syncing with active namenode to keep latest FSimage. In HA environment active namenode writes edit log into journal node and standby node go and get the edit log and create new FSimage.

[hdfs@datanode1 ~]$ hdfs dfsadmin -safemode get Safe mode is OFF

[hdfs@datanode1 ~]$ […]

RHEL 5 vs RHEL 7 comparision

Command changes for common tasks System basics Task RHEL5 RHEL7 View subscription information /etc/sysconfig/rhn/systemid subscription-manager identity Configure subscription rhn_register subscription-manager rhn_register View system profile sosreport dmidecode hwbrowser sosreport dmidecode lstopo lscpu Basic configuration Task RHEL5 RHEL7 Graphical configuration tools system-config-* gnome-control-center Configure network system-config-network nmcli nmtui nm-connection-editor Configure system language system-config-language localectl Configure time and […]

RHEL 7 – Changed mount behavior at boot – Nofail

Earlier versions of Red Hat Enterprise Linux booted regardless of whether all partitions specified in /etc/fstab could be mounted. This could result in a system appearing “up” and healthy, while booting without required partitions. To prevent this situation, in Red Hat Enterprise Linux 7, if a partition defined in /etc/fstab cannot be mounted at […]

RHEL 7 reset root password

If you lost the root password to the system and you have access to the boot loader, you can reset the password by editing the GRUB2 configuration.

Resetting the Root Password

Boot your system and wait until the GRUB2 menu appears. In the boot loader menu, highlight any entry and press e to […]

RHEL 7 XFS command vs EXT4

Task ext4 XFS Creating a file system mkfs.ext4 mkfs.xfs Mounting a file system mount mount Resizing a file system resize2fs xfs_growfs Repairing a file system e2fsck xfs_repair Changing the label on a file system e2label xfs_admin -L Reporting on disk space and file usage quota quota Debugging a file system debugfs xfs_db Store critical […]