GlusterFS / CTDB Integration

[Pages:34]GlusterFS / CTDB Integration

v1.0 2013.05.14 Etsuji Nakai

Senior Solution Architect Red Hat K.K.

Red Hat K.K. All rights reserved.

$ who am i

Etsuji Nakai (@enakai00)

Senior solution architect and cloud evangelist at Red Hat K.K.

The author of "Professional Linux Systems" series.

Available in Japanese. Translation offering from publishers are welcomed ;-)

Professional Linux Systems Technology for Next Decade

Professional Linux Systems Deployment and Management

Professional Linux Systems Network Management

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2

Contents

CTDB Overview Why does CTDB matter? CTDB split-brain resolution Configuration steps for demo set-up Summary

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Disclaimer

This document explains how to setup clustered Samba server using GlusterFS and CTDB with the following software components. Base OS, Samba, CTDB: RHEL6.4 (or any of your favorite clone) GlusterFS: GlusterFS 3.3.1 (Community version)

Since this is based on the community version of GlusterFS, you cannot receive a commercial support from Red Hat for this configuration. If you need a commercial support, please consider using Red Hat Storage Server(RHS). In addition, there are different conditions for a supportable configuration with RHS. Please consult sales representatives from Red Hat for details.

Red Hat accepts no liability for the content of this document, or for the consequences of any actions taken on the basis of the information provided. Any views or opinions presented in this document are solely those of the author and do not necessarily represent those of Red Hat.

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CTDB Overview

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What's CTDB?

TDB = Trivial Database

Simple backend DB for Samba, used to store user info, file lock info, etc...

CTDB = Clustered TDB

Cluster extension of TDB, necessary for multiple Samba hosts configuration to provide the same filesystem contents.

All clients see the same contents through different Samba hosts.

Samba

Samba

Samba

Shared Filesystem

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What's wrong without CTDB?

Windows file locks are not shared among Samba hosts.

You would see the following alert when someone is opening the same file.

Without CTDB, if others are opening the same file through a different Samba host from you, you never see that alert.

This is because file lock info is stored in the local TDB if you don't use CTDB.

Locked!

Locked!

CTDB was initially developed as a shared TDB for multiple Samba hosts to overcome this problem.

Windows file locks are not shared.

xxx.xls

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Yet another benefit of CTDB

Floating IP's can be assigned across hosts for the transparent failover.

When one of the hosts fails, the floating IP is moved to another host.

Mutual health checking is done through the CTDB interconnect (so called "heartbeat") network.

CTDB can also be used for NFS server cluster to provide the floating IP feature. (CTDB doesn't provide shared file locking for NFS though.)

Floating IP#1

Floating IP#2

Floating IP#N

CTDB interconnect (heartbeat) network

Floating IP#1

Floating IP#1

Floating IP#2

Floating IP#N

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