Accumulo 2.x Documentation  >>  Administration  >>  Upgrading Accumulo

Upgrading Accumulo

Upgrading from 1.8/9 to 2.0

Follow the steps below to upgrade your Accumulo instance and client to 2.0.

Upgrade Accumulo instance

IMPORTANT! Before upgrading to Accumulo 2.0, you will need to upgrade to Java 8 and Hadoop 3.x.

Upgrading to Accumulo 2.0 is done by stopping Accumulo 1.8/9 and starting Accumulo 2.0.

Before stopping Accumulo 1.8/9, install Accumulo 2.0 and configure it by following the 2.0 install instructions.

There are several changes to scripts and configuration in 2.0 so be careful when using configuration or automated setup designed for 1.8/9. Below are some changes in 2.0 that you should be aware of:

  • accumulo.properties has replaced accumulo-site.xml. You can either convert accumulo-site.xml by hand from XML to properties or use the following Accumulo command.
    accumulo convert-config -x old/accumulo-site.xml -p new/accumulo.properties
    
  • accumulo-client.properties has replaced client.conf. The client properties in the new file are different so take care when customizing.
  • accumulo-cluster script has replaced the start-all.sh & stop-all.sh scripts.
    • Default host files (i.e masters, monitor, gc) are no longer in conf/ directory of tarball but can be created using accumulo-cluster create-config
    • Tablet server hosts must be listed in a tservers file instead of a slaves file. To minimize confusion, Accumulo will not start if the old slaves file is present.
  • accumulo-service script can be used to start/stop Accumulo services (i.e master, tablet server, monitor) on a single node.
    • Can be used even if Accumulo was started using accumulo-cluster script.
  • accumulo-env.sh constructs environment variables (such as JAVA_OPTS and CLASSPATH) used when running Accumulo processes
    • This file was used in Accumulo 1.x but has changed signficantly for 2.0
    • Environment variables (such as $cmd, $bin, $conf) are set before accumulo-env.sh is loaded and can be used to customize environment.
    • The JAVA_OPTS variable is constructed in accumulo-env.sh to pass command-line arguments to the java command that the starts Accumulo processes (i.e. java $JAVA_OPTS main.class.for.$cmd).
    • The CLASSPATH variable sets the Java classpath used when running Accumulo processes. It can be modified to upgrade dependencies or use vendor-specific distributions of Hadoop.
  • Logging is configured in accumulo-env.sh for Accumulo processes. The following log4j configuration files in the conf/ directory will be used if accumulo-env.sh is not modified. These files can be modified to turn on/off logging for Accumulo processes:
    • log4j-service.properties for all Accumulo services (except monitor)
    • logj4-monitor.properties for Accumulo monitor
    • log4j.properties for Accumulo clients and commands
  • Run the command accumulo shell to access the shell using configuration in conf/accumulo-client.properties

When your Accumulo 2.0 installation is properly configured, stop Accumulo 1.8/9 and start Accumulo 2.0:

./accumulo-1.9.2/bin/stop-all.sh
./accumulo-2.0.0/bin/accumulo-cluster start

It is recommended that users test this upgrade on development or test clusters before attempting it on production clusters.

Upgrade Accumulo clients

There several client API changes in 2.0. In most cases, new API was introduced and the old API was only deprecated. While it is recommended that users start using the new API, the old API will continue to be supported through 2.x.

Below is a list of client API changes that users are required to make for 2.0:

  • Update your pom.xml use Accumulo 2.0. Also, update any Hadoop & ZooKeeper dependencies in your pom.xml to match the versions runing on your cluster.
    <dependency>
      <groupId>org.apache.accumulo</groupId>
      <artifactId>accumulo-core</artifactId>
      <version>2.0.0</version>
    </dependency>
    
  • ClientConfiguration objects can no longer be ceated using new ClientConfiguration().
    • Use ClientConfiguration.create() instead
  • Some API deprecated in 1.x releases was dropped
  • Aggregators have been removed

Below is a list of recommended client API changes:

Upgrading from 1.7 to 1.8

Upgrades from 1.7 to 1.8 are possible with little effort as no changes were made at the data layer and RPC changes were made in a backwards-compatible way. The recommended way is to stop Accumulo 1.7, perform the Accumulo upgrade to 1.8, and then start 1.8. Like previous versions, after 1.8 is started on a 1.7 instance, a one-time upgrade will happen by the Master which will prevent a downgrade back to 1.7. Upgrades are still one way. Upgrades from versions prior to 1.7 to 1.8 should follow the below path to 1.7 and then perform the upgrade to 1.8 – direct upgrades to 1.8 for versions other than 1.7 are untested.

Existing configuration files from 1.7 should be compared against the examples provided in 1.8. The 1.7 configuration files should all function with 1.8 code, but you will likely want to include changes found in the 1.8.0 release notes and these release notes for 1.8.1.

For upgrades from prior to 1.7, follow the upgrade instructions to 1.7 first.

Upgrading from 1.7.x to 1.7.y

The recommended way to upgrade from a prior 1.7.x release is to stop Accumulo, upgrade to 1.7.y and then start 1.7.y.

When upgrading, there is a known issue if the upgrade fails due to outstanding FATE operations, see ACCUMULO-4496 The work around if this situation is encountered:

  • Start tservers
  • Start shell
  • Run fate print to list all
  • If completed, just delete with fate delete
  • Start masters once there are no more fate operations

If any of the FATE operations are not complete, you should rollback the upgrade and troubleshoot completing them with your prior version. When performing an upgrade between major versions, the upgrade is one-way, therefore it is important that you do not have any outstanding FATE operations before starting the upgrade.

Upgrading from 1.6 to 1.7

Upgrades from 1.6 to 1.7 are possible with little effort as no changes were made at the data layer and RPC changes were made in a backwards-compatible way. The recommended way is to stop Accumulo 1.6, perform the Accumulo upgrade to 1.7, and then start 1.7. Like previous versions, after 1.7.0 is started on a 1.6 instance, a one-time upgrade will happen by the Master which will prevent a downgrade back to 1.6. Upgrades are still one way. Upgrades from versions prior to 1.6 to 1.7 should follow the below path to 1.6 and then perform the upgrade to 1.7 – direct upgrades to 1.7 for versions other than 1.6 are untested.

After upgrading to 1.7.0, users will notice the addition of a replication table in the accumulo namespace. This table is created and put offline to avoid any additional maintenance if the data-center replication feature is not in use.

Existing configuration files from 1.6 should be compared against the examples provided in 1.7. The 1.6 configuration files should all function with 1.7 code, but you will likely want to include a new file (hadoop-metrics2-accumulo.properties) to enable the new metrics subsystem. Read the section on Hadoop Metrics2 in the Administration chapter of the Accumulo User Manual.

For each of the other new features, new configuration properties exist to support the feature. Refer to the added sections in the User Manual for the feature for information on how to properly configure and use the new functionality.

Upgrading from 1.5 to 1.6

This happens automatically the first time Accumulo 1.6 is started.

If your instance previously upgraded from 1.4 to 1.5, you must verify that your 1.5 instance has no outstanding local write ahead logs. You can do this by ensuring either:

  • All of your tables are online and the Monitor shows all tablets hosted
  • The directory for write ahead logs (logger.dir.walog) from 1.4 has no files remaining on any tablet server / logger hosts

To upgrade from 1.5 to 1.6 you must:

  • Verify that there are no outstanding FATE operations
    • Under 1.5 you can list what’s in FATE by running $ACCUMULO_HOME/bin/accumulo org.apache.accumulo.server.fate.Admin print
    • Note that operations in any state will prevent an upgrade. It is safe to delete operations with status SUCCESSFUL. For others, you should restart your 1.5 cluster and allow them to finish.
  • Stop the 1.5 instance.
  • Configure 1.6 to use the hdfs directory and zookeepers that 1.5 was using.
  • Copy other 1.5 configuration options as needed.
  • Start Accumulo 1.6.

The upgrade process must make changes to Accumulo’s internal state in both ZooKeeper and the table metadata. This process may take some time if Tablet Servers have to go through recovery. During this time, the Monitor will claim that the Master is down and some services may send the Monitor log messages about failure to communicate with each other. These messages are safe to ignore. If you need detail on the upgrade’s progress you should view the local logs on the Tablet Servers and active Master.

Upgrading from 1.4 to 1.6

To upgrade from 1.4 to 1.6 you must perform a manual initial step.

Prior to upgrading you must:

  • Verify that there are no outstanding FATE operations
    • Under 1.4 you can list what’s in FATE by running $ACCUMULO_HOME/bin/accumulo org.apache.accumulo.server.fate.Admin print
    • Note that operations in any state will prevent an upgrade. It is safe to delete operations with status SUCCESSFUL. For others, you should restart your 1.4 cluster and allow them to finish.
  • Stop the 1.4 instance.
  • Configure 1.6 to use the hdfs directory, walog directories, and zookeepers that 1.4 was using.
  • Copy other 1.4 configuration options as needed.

Prior to starting the 1.6 instance you will need to run the LocalWALRecovery tool on each node that previously ran an instance of the Logger role.

$ACCUMULO_HOME/bin/accumulo org.apache.accumulo.tserver.log.LocalWALRecovery

The recovery tool will rewrite the 1.4 write ahead logs into a format that 1.6 can read. After this step has completed on all nodes, start the 1.6 cluster to continue the upgrade.

The upgrade process must make changes to Accumulo’s internal state in both ZooKeeper and the table metadata. This process may take some time if Tablet Servers have to go through recovery. During this time, the Monitor will claim that the Master is down and some services may send the Monitor log messages about failure to communicate with each other. While the upgrade is in progress, the Garbage Collector may complain about invalid paths. The Master may also complain about failure to create the trace table because it already exists. These messages are safe to ignore. If other error messages occur, you should seek out support before continuing to use Accumulo. If you need detail on the upgrade’s progress you should view the local logs on the Tablet Servers and active Master.

Note that the LocalWALRecovery tool does not delete the local files. Once you confirm that 1.6 is successfully running, you should delete these files on the local filesystem.

Upgrading from 1.4 to 1.5

This happens automatically the first time Accumulo 1.5 is started.

  • Stop the 1.4 instance.
  • Configure 1.5 to use the hdfs directory, walog directories, and zookeepers that 1.4 was using.
  • Copy other 1.4 configuration options as needed.
  • Start Accumulo 1.5.
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