Features/GFS2ClusteredSamba

Clustered Samba for GFS2

Summary

Support for clustered samba (including active/active configuration) over GFS2 using CTDB.

Owner

• Name: Abhijith Das
• email: adas@redhat.com

Current status

• Targeted release: Fedora 12
• Last updated: 7/20/2009
• Percentage of completion: 70%

Detailed Description

With the availability of a clustered database (CTDB) for Samba, multiple instances of smbd across different nodes of a cluster are able to share state. It is now possible to export a gfs2 filesystem through one or more nodes in the cluster in a active/passive or active/active configuration to provide a highly-available Samba service.

Benefit to Fedora

Samba was not cluster-aware until the introduction of CTDB and hence it was not possible to have a highly available samba service. Particularly, active/active configuration was not possible. With this feature, it will be possible to run highly available samba service(s) with different configurations (active/active, active/passive) over a shared gfs2 filesystem on the Red Hat cluster infrastructure.

Scope

• Verify simple functionality by exporting samba shares over gfs2 and running smbtorture tests (in progress)
• fcntl posix locks performance: Improve upon gfs2's posix lock performance (single-node & clustered) as smbd uses them extensively when posix locking is turned on. (in progress)
• Get CTDB and CTDB-supported Samba packages into F12. (complete)
• Get Conga interface ready for manipulating the various config files (/etc/cluster/cluster.conf, /etc/sysconfig/ctdb, /etc/samba/smb.conf) through web-based GUI. (Alternative to hand-editing configs) (in progress)
• Verify working of clustered samba use cases such as service failover, recovery, etc., and document respective configuration parameters. (in progress)

This feature will not affect the operation of non-clustered samba setups or other gfs2-based setups. It will provide the capability to setup clustered samba over gfs2.

How To Test

1. smbtorture tests like RAW_BENCH_LOCK (posix locking = on), RAW_BENCH_OPEN, BENCH_NBENCH and the ctdb ping_pong test are to be run on a samba+ctdb+gfs2 cluster.

• Basic Configuration:
  • Setup a cluster with your machines: <link>
  • mount a gfs2-formatted clustered volume at the same mountpoint on all nodes.
  • export this mountpoint (or a directory within it) as a samba share. All smb.conf files in all nodes should be identical
  • Set ctdb configuration <link>
  • start the ctdb service and check 'ctdb status' to make sure the ctdb cluster is up.
  • Now you should simultaneously be able to access the samba share through all the exporting nodes and run operations on them simultaneously.

User Experience

Users not using gfs2, samba or ctdb should notice no change. Users will now have the ability to run a clustered samba setup exporting gfs2 shares.

Dependencies

Most of the kernel support (gfs2 filesystem) is already upstream. ctdb and samba packages have been included in Fedora.

Contingency Plan

In it's current state, a basic clustered samba setup should work. Enhancements such as posix lock performance & conga interface and testing of different use-cases would be nice to get done with. If not done with these tasks, in it's current form, the feature is still acceptable.

Documentation

• ctdb
• samba
• Cluster Suite on Wikipedia
• GFS/GFS2 on Wikipedia
• Cluster Wiki page
• GFS2 kernel documentation (a very basic introduction)

Release Notes

• Fedora now has support for clustered samba over gfs2

Comments and Discussion

• See Talk:Features/GFS2ClusteredSamba