Rolling Upgrades For Riak CS

Each node in a Riak CS cluster contains settings that define its operating modes and API coverage. The following steps outline the process of upgrading Riak CS in a rolling fashion.

Be sure to check the Riak CS Version Compatibility chart to ensure that your version of Riak, Riak CS, and Stanchion have been tested to work together. As Riak supports upgrades from the previous two major versions, this document will cover upgrades from Riak CS 1.4.x and Riak CS 1.5.x.

As Riak CS 2.0.0 only works with Riak 2.0.5, the underlying Riak installation must be upgraded to Riak 2.0.5.

Note on upgrading from Riak CS < 1.5.4

Some key objects changed names after the upgrade. Applications may need to change their behaviour due to this bugfix.

Note on upgrading from Riak CS < 1.5.1

Bucket number limitation per user have been introduced in 1.5.1. Users who have more than 100 buckets cannot create any bucket after the upgrade unless the limit is extended in the system configuration.

Note on upgrading From Riak CS 1.4.x

An operational procedure to clean up incomplete multipart under deleted buckets is needed. Otherwise new buckets with names that used to exist in the past can’t be created. The operation will fail with a 409 Conflict error.

Leeway seconds and disk space should also be carefully watched during the upgrade, because timestamp management of garbage collection has changed since the 1.5.0 release. Consult the Leeway seconds and disk space section of the 1.5 release notes for a more detailed description.

Stop Riak, Riak CS, and Stanchion:
```
riak stop
riak-cs stop
stanchion stop
```

Back up Riak’s configuration files:

sudo tar -czf riak_config_backup.tar.gz /etc/riak

Optionally, back up your data directories:
```
sudo tar -czf riak_data_backup.tar.gz /var/lib/riak
```
Note on Patches
Remember to remove all patches from the `basho-patches` directory, as the version of Erlang has changed in Riak CS 2.0. All official patches previously released by Riak have been included in this release.

Upgrade Riak, Riak CS, and Stanchion. See the Riak CS Downloads and Riak Downloads pages to find the appropriate packages.

Debian / Ubuntu

sudo dpkg -i <riak_package_name>.deb
sudo dpkg -i <riak-cs_package_name>.deb
sudo dpkg -i <stanchion_package_name>.deb

RHEL / CentOS

sudo rpm -Uvh <riak_package_name>.rpm
sudo rpm -Uvh <riak-cs_package_name>.rpm
sudo rpm -Uvh <stanchion_package_name>.rpm

The add_paths setting in your configuration file must be updated to reflect the current version’s /ebin directory. To give an example, if the previous /ebin directory was located at /usr/lib/riak-cs/lib/riak_cs-1.5.2/ebin and you’re upgrading to version 2.0.0, you will need to change the value in add_paths:
```
{add_paths, ["/usr/lib/riak-cs/lib/riak_cs-2.0.0/ebin"]}
```
```
{add_paths, ["/usr/lib/riak-cs/lib/riak_cs-2.0.0/ebin"]}
```
Riak CS 2.0 introduces a new style of configuration known as riak-cs.conf. You may choose to continue the use of the app.config file, or migrate your existing configuration to riak-cs.conf (recommended). If you choose to use riak-cs.conf, you should migrate all supported settings to the new format, and copy all others to the new advanced.config file.

Note on Legacy app.config usage

If you choose to use the legacy app.config files for Riak CS and/or Stanchion, some parameters have changed names and must be updated.

In particular, for the Riak CS app.config:

cs_ip and cs_port have been combined into listener.
riak_ip and riak_pb_port have been combined into riak_host.
stanchion_ip and stanchion_port have been combined into stanchion_host.
admin_ip and admin_port have been combined into admin_listener.
webmachine_log_handler has become webmachine_access_log_handler.
{max_open_files, 50} has been deprecated and should be replaced with {total_leveldb_mem_percent, 30}.

For the Stanchion app.config:

stanchion_ip and stanchion_port have been combined into listener.
riak_ip and riak_port have been combined into riak_host.

Each of the above pairs follows a similar form. For example, if your legacy app.config configuration was previously:

  {riak_cs, [`
      {cs_ip, "127.0.0.1"},
      {cs_port, 8080 },
      . . .
  ]},

It should now read:

  {riak_cs, [
      {listener, {"127.0.0.1", 8080}},
      . . .
  ]},

and so on. More details can be found at configuring Riak CS.

Note on Memory Sizing

Some changes have been made to both Riak and Riak CS that may warrant some performance tuning. Please consult the Release Notes for more details.

Riak has also moved to the new configuration format, using a file called riak.conf. Remember to migrate all existing Riak configurations during the upgrade process. For example, the default bucket properties:
```
buckets.default.allow_mult = true
```
```
{riak_core, [
   ...
   {default_bucket_props, [{allow_mult, true}]},
   ...
]}.
```

Start the node:

riak start
stanchion start
riak-cs start

Wait for any handoff to complete:
```
riak-admin transfers
```
Move on to the next node and repeat this process throughout the cluster.