1. Getting Ready to Upgrade - Hortonworks Data Platform

Stop all services (including MapReduce) and client applications deployed on HDFS using the instructions provided here.

Run the fsck command as instructed below and fix any errors. (The resulting file will contain complete block map of the file system.)

hadoop fsck / -files -blocks -locations > dfs-old-fsck-1.log

Use the following instructions to compare the status before and after the upgrade:

	Note
	The following commands must be executed by the user running the HDFS service (by default, the user is `hdfs`).

Capture the complete namespace of the file system. (The following command does a recursive listing of the root file system. )
```
su hdfs
hadoop dfs -lsr / > dfs-old-lsr-1.log 
```
Run report command to create a list of DataNodes in the cluster.
```
su hdfs
hadoop dfsadmin -report > dfs-old-report-1.log
```
Optionally, copy all or unrecoverable data stored in DFS to a local file system or to a backup instance of DFS.
Optionally, repeat the steps 3 (a) through 3 (c) and compare the results with the previous run to ensure the state of the file system remained unchanged.

As HDFS user, execute the following command to save namespace:

hadoop dfsadmin -saveNamespace

Copy the following checkpoint files into a backup directory:

dfs.name.dir/edits
dfs.name.dir/image/fsimage

Stop the HDFS. Ensure all the HDP services in the cluster are completely stopped at this point.

If upgrading Hive, ensure that you back up the Hive database.

Configure the local repositories.

The standard HDP install fetches the software from a remote yum repository over the Internet. To use this option, you must set up access to the remote repository and have an available Internet connection for each of your hosts.

	Note
	If your cluster does not have access to the Internet, or you are creating a large cluster and you want to conserve bandwidth, you can instead provide a local copy of the HDP repository that your hosts can access. For more information, see Deployment Strategies for Data Centers with Firewalls., a separate document in this set.

For each node in your cluster, download the yum repo configuration file hdp.repo. From a terminal window, type:

For RHEL and CentOS 5

wget  http://public-repo-1.hortonworks.com/HDP-1.2.0/repos/centos5/hdp.repo -O /etc/yum.repos.d/hdp.repo

For RHEL and CentOS 6

wget  http://public-repo-1.hortonworks.com/HDP-1.2.0/repos/centos6/hdp.repo -O /etc/yum.repos.d/hdp.repo

For SLES 11

wget  http://public-repo-1.hortonworks.com/HDP-1.2.0/repos/suse11/hdp.repo -O /etc/zypp/repos.d/hdp.repo

Confirm the HDP repository is configured by checking the repo list.
- For RHEL/CentOS:
```
yum repolist
```
- For SLES:
```
zypper repos
```