Before You Begin

• Read the Cloudera Manager 5 Release Notes.
• Make sure there are no Oozie workflows in RUNNING or SUSPENDED status; otherwise the Oozie database upgrade will fail and you will have to reinstall CDH 4 to complete or kill those running workflows.
• Run the Host Inspector and fix every issue.
• If using security, run the Security Inspector.
• Run hdfs fsck / and hdfs dfsadmin -report and fix any issues.
• If using HBase:
  • Run hbase hbck to make sure there are no inconsistencies.
  • Before you can upgrade HBase from CDH 4 to CDH 5, your HFiles must be upgraded from HFile v1 format to HFile v2, because CDH 5 no longer supports HFile v1. The upgrade procedure itself is different if you are using Cloudera Manager or the command line, but has the same results. The first step is to check for instances of HFile v1 in the HFiles and mark them to be upgraded to HFile v2, and to check for and report about corrupted files or files with unknown versions, which need to be removed manually. The next step is to rewrite the HFiles during the next major compaction. After the HFiles are upgraded, you can continue the upgrade. To check and upgrade the files:
    1. In the Cloudera Admin Console, go to the HBase service and run Actions > Check HFile Version.
    2. Check the output of the command in the stderr log.
       Your output should be similar to the following:

       Tables Processed:
       hdfs://localhost:41020/myHBase/.META.
       hdfs://localhost:41020/myHBase/usertable
       hdfs://localhost:41020/myHBase/TestTable
       hdfs://localhost:41020/myHBase/t
       
       Count of HFileV1: 2
       HFileV1:
       hdfs://localhost:41020/myHBase/usertable /fa02dac1f38d03577bd0f7e666f12812/family/249450144068442524
       hdfs://localhost:41020/myHBase/usertable /ecdd3eaee2d2fcf8184ac025555bb2af/family/249450144068442512
       
       Count of corrupted files: 1
       Corrupted Files:
       hdfs://localhost:41020/myHBase/usertable/fa02dac1f38d03577bd0f7e666f12812/family/1
       Count of Regions with HFileV1: 2
       Regions to Major Compact:
       hdfs://localhost:41020/myHBase/usertable/fa02dac1f38d03577bd0f7e666f12812
       hdfs://localhost:41020/myHBase/usertable/ecdd3eaee2d2fcf8184ac025555bb2af

       In the example above, you can see that the script has detected two HFile v1 files, one corrupt file and the regions to major compact.
    3. Trigger a major compaction on each of the reported regions. This major compaction rewrites the files from HFile v1 to HFile v2 format. To run the major compaction, start HBase Shell and issue the major_compact command.

       $ bin/hbase shell
       hbase> major_compact 'usertable'

       You can also do this in a single step by using the echo shell built-in command.

       $ echo "major_compact 'usertable'" | bin/hbase shell

• Review the upgrade procedure and reserve a maintenance window with enough time allotted to perform all steps. For production clusters, Cloudera recommends allocating up to a full day maintenance window to perform the upgrade, depending on the number of hosts, the amount of experience you have with Hadoop and Linux, and the particular hardware you are using.
• To avoid generating many alerts during the upgrade process, you can enable maintenance mode on your cluster before you start the upgrade. Be sure to exit maintenance mode when you have finished the upgrade, in order to re-enable Cloudera Manager alerts.
• Put the NameNode into safe mode. To upgrade CDH in multiple clusters, repeat this process for each cluster:
  1. In the Cloudera Manager Admin Console, go the HDFS service, NameNode role instance.
  2. Select Actions > Enter Safemode... and confirm that you want to do this.
  3. After the NameNode has successfully entered safemode, select Actions > Save Namespace... and confirm that you want to do this. This will result in a new fsimage being written out with no edit log entries. Leave the NameNode in safe mode while you proceed with the upgrade instructions.
• Ensure Java 7 is installed across the cluster. CDH 5 requires Java 7, and some services may not start if it is not installed. For installation instructions and recommendations for CDH 5, see (CDH 5) Java Development Kit Installation.
• Back up important databases:
  • Cloudera Manager databases. For instructions, see Backing up Databases. You will need to indicate to the upgrade wizard that you have performed this step before the upgrade will proceed.
  • Hive Metastore database (which could be in the embedded database)
  • Hue database
  • Oozie database
  • Sqoop database
• If you have just upgraded to Cloudera Manager 5, you must hard restart the Cloudera Manager Agents as described in the Hard Restart Cloudera Manager Agents task in Upgrading Cloudera Manager 4 to Cloudera Manager 5 in Cloudera Manager Administration Guide.

Stop All Services

1. Stop each cluster.
   1. On the Home page, click to the right of the cluster name and select Stop.
   2. Click Stop in the confirmation screen. The Command Details window shows the progress of stopping services.

      When All services successfully stopped appears, the task is complete and you can close the Command Details window.

2. Stop the Cloudera Management Service:
   1. Do one of the following:
      • 1. Select Clusters > Cloudera Management Service > Cloudera Management Service.
        2. Select Actions > Stop.
      • 1. On the Home page, click to the right of Cloudera Management Service and select Stop.
   2. Click Stop to confirm. The Command Details window shows the progress of stopping the roles.
   3. When Command completed with n/n successful subcommands appears, the task is complete. Click Close.

Perform Service-Specific Prerequisite Actions

• Accumulo - if you have installed the Accumulo parcel, deactivate it following the instructions in Managing Parcels.
• HDFS - Back up HDFS metadata on the NameNode:
  1. Stop the NameNode you want to back up.
  2. Go to the HDFS service.
  3. Click the Configuration tab.
  4. In the Search field, search for "NameNode Data Directories". This locates the NameNode Data Directories property.
  5. From the command line on the NameNode host, back up the directory listed in the NameNode Data Directories property. If more than one is listed, then you only need to make a backup of one directory, since each directory is a complete copy. For example, if the data directory is /mnt/hadoop/hdfs/name, do the following as root:

     # cd /mnt/hadoop/hdfs/name
     # tar -cvf /root/nn_backup_data.tar .

     You should see output like this:

     ./
     ./current/
     ./current/fsimage
     ./current/fstime
     ./current/VERSION
     ./current/edits
     ./image/
     ./image/fsimage

       Warning: If you see a file containing the word lock, the NameNode is probably still running. Repeat the preceding steps, starting by shutting down the CDH services.

Remove CDH Packages

Deactivate and Remove the GPL Extras Parcel

Run the Upgrade Wizard

Import MapReduce Configuration to YARN

In CDH 5 and Cloudera Manager 5, YARN rather than MapReduce is the default MapReduce computation framework. If you had the MapReduce service configured in CDH 4, you can import the MapReduce configuration to YARN. This does not affect your MapReduce configuration.

  Warning: In addition to importing configuration settings, the import process:

• Configures services to use YARN as the MapReduce computation framework instead of MapReduce.
• Overwrites existing YARN configuration and role assignments.

1. To import the existing configuration from your MapReduce service, select OK, set up YARN to add the YARN service and import the MapReduce settings. To skip the import, select Skip this step now. If you choose to skip this step, you can perform it at a later time from the YARN service.
2. Click Continue to proceed. Cloudera Manager stops the YARN service (if running) and its dependencies. When these commands complete, click Continue.
3. The next page indicates some additional configuration required by YARN. Verify or modify these and click Continue.
4. The Switch Cluster to MR2 step proceeds. When all steps have been completed, click Continue.
5. When all steps have complete, click Continue.

Upgrade the GPL Extras Parcel

Restart the Reports Manager Role

1. Do one of the following:
   • Select Clusters > Cloudera Management Service > Cloudera Management Service.
   • On the Status tab of the Home page, in Cloudera Management Service table, click the Cloudera Management Service link.
2. Click the Instances tab.
3. Check the checkbox next to Reports Manager.
4. Select Actions for Selected > Restart and then Restart to confirm.

Recompile HBase Coprocessor and Custom JARs

Finalize the HDFS Metadata Upgrade