neoppod 0.9

Overview

A NEO cluster is composed of the following types of nodes:

• “master” nodes (mandatory, 1 or more)

  Takes care of transactionality. Only one master node is really active (the active master node is called “primary master”) at any given time, extra masters are spares (they are called “secondary masters”).

• “storage” nodes (mandatory, 1 or more)

  Stores data in a MySQL database, preserving history. All available storage nodes are in use simultaneously. This offers redundancy and data distribution. Other storage backends than MySQL are considered for future release.

• “admin” nodes (mandatory for startup, optional after)

  Accepts commands from neoctl tool and transmits them to the primary master, and monitors cluster state.

• “client” nodes

  Well… Something needing to store/load data in a NEO cluster.

ZODB API is fully implemented except:

• pack: only old revisions of objects are removed for the moment

  (full implementation is considered)

• blobs: not implemented (not considered yet)

There is a simple way to convert FileStorage to NEO and back again.

See also http://www.neoppod.org/links for more detailed information about features related to scalability.

Disclaimer

In addition of the disclaimer contained in the licence this code is released under, please consider the following.

NEO does not implement any authentication mechanism between its nodes, and does not encrypt data exchanged between nodes either. If you want to protect your cluster from malicious nodes, or your data from being snooped, please consider encrypted tunelling (such as openvpn).

Requirements

• Linux 2.6 or later

• Python 2.4 or later

• For python 2.4: ctypes http://python.net/crew/theller/ctypes/ (packaged with later python versions)

  Note that setup.py does not define any dependency to ‘ctypes’ so you will have to install it explicitely.

• For storage nodes:

  • MySQLdb: http://sourceforge.net/projects/mysql-python

• For client nodes: ZODB 3.10.x but it should work with ZODB >= 3.4

Installation

1. Make neo directory available for python to import (for example, by adding its container directory to the PYTHONPATH environment variable).

2. Choose a cluster name and setup a MySQL database

3. Start all required nodes:

   neomaster --cluster=<cluster name>
   neostorage --cluster=<cluster name> --database=user:passwd@host
   neoadmin --cluster=<cluster name>

4. Tell the cluster it can provide service:

   neoctl start

How to use

First make sure Python can import ‘neo.client’ package.

from neo.client.Storage import Storage
s = Storage(master_nodes="127.0.0.1:10010", name="main")
...

Deployment

NEO has no built-in deployment features such as process daemonization. We use supervisor with configuration like below:

[group:neo]
programs=master_01,storage_01,admin

[program:master_01]
priority=1
command=neomaster -c neo -s master_01 -f /neo/neo.conf
user=neo

[program:storage_01]
priority=2
command=neostorage -c neo -s storage_01 -f /neo/neo.conf
user=neo

[program:admin]
priority=3
command=neoadmin -c neo -s admin -f /neo/neo.conf
user=neo

Developers

Developers interested in NEO may refer to NEO Web site and subscribe to following mailing lists:

• neo-users: users discussion

• neo-dev: developers discussion

• neo-report: automated test results (read-only list)

Commercial Support

Nexedi provides commercial support for NEO: http://www.nexedi.com/

Change History

0.9 (2011-09-12)

Initial release.

NEO is considered stable enough to replace existing ZEO setups, except that:

• there’s no backup mechanism (aka efficient snapshoting): there’s only replication and underlying MySQL tools

• MySQL tables format may change in the future