Red Hat Enterprise Linux 6

Global File System 2

Red Hat Global File System 2

Edition 7

Legal Notice

Copyright © 2013 Red Hat, Inc. and others.
This document is licensed by Red Hat under the Creative Commons Attribution-ShareAlike 3.0 Unported License. If you distribute this document, or a modified version of it, you must provide attribution to Red Hat, Inc. and provide a link to the original. If the document is modified, all Red Hat trademarks must be removed.
Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law.
Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss, MetaMatrix, Fedora, the Infinity Logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries.
Linux® is the registered trademark of Linus Torvalds in the United States and other countries.
Java® is a registered trademark of Oracle and/or its affiliates.
XFS® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries.
MySQL® is a registered trademark of MySQL AB in the United States, the European Union and other countries.
Node.js® is an official trademark of Joyent. Red Hat Software Collections is not formally related to or endorsed by the official Joyent Node.js open source or commercial project.
The OpenStack® Word Mark and OpenStack Logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endorsed or sponsored by the OpenStack Foundation, or the OpenStack community.
All other trademarks are the property of their respective owners.

Abstract

This book provides information about configuring and maintaining Red Hat GFS2 (Red Hat Global File System 2) for Red Hat Enterprise Linux 6.
Introduction
1. Audience
2. Related Documentation
3. We Need Feedback!
4. Document Conventions
4.1. Typographic Conventions
4.2. Pull-quote Conventions
4.3. Notes and Warnings
1. GFS2 Overview
1.1. New and Changed Features
1.1.1. New and Changed Features for Red Hat Enterprise Linux 6.0
1.1.2. New and Changed Features for Red Hat Enterprise Linux 6.1
1.1.3. New and Changed Features for Red Hat Enterprise Linux 6.2
1.1.4. New and Changed Features for Red Hat Enterprise Linux 6.3
1.1.5. New and Changed Features for Red Hat Enterprise Linux 6.4
1.2. Before Setting Up GFS2
1.3. Differences between GFS and GFS2
1.3.1. GFS2 Command Names
1.3.2. Additional Differences Between GFS and GFS2
1.3.3. GFS2 Performance Improvements
2. GFS2 Configuration and Operational Considerations
2.1. Formatting Considerations
2.1.1. File System Size: Smaller is Better
2.1.2. Block Size: Default (4K) Blocks Are Preferred
2.1.3. Number of Journals: One for Each Node that Mounts
2.1.4. Journal Size: Default (128MB) Is Usually Optimal
2.1.5. Size and Number of Resource Groups
2.2. File System Fragmentation
2.3. Block Allocation Issues
2.3.1. Leave Free Space in the File System
2.3.2. Have Each Node Allocate its Own Files, If Possible
2.3.3. Preallocate, If Possible
2.4. Cluster Considerations
2.5. Usage Considerations
2.5.1. Mount Options: noatime and nodiratime
2.5.2. DLM Tuning Options: Increase DLM Table Sizes
2.5.3. VFS Tuning Options: Research and Experiment
2.5.4. SELinux: Avoid SELinux on GFS2
2.5.5. Setting Up NFS Over GFS2
2.5.6. Samba (SMB or Windows) File Serving over GFS2
2.6. File System Backups
2.7. Hardware Considerations
2.8. Performance Issues: Check the Red Hat Customer Portal
2.9. GFS2 Node Locking
2.9.1. Issues with Posix Locking
2.9.2. Performance Tuning With GFS2
2.9.3. Troubleshooting GFS2 Performance with the GFS2 Lock Dump
3. Getting Started
3.1. Prerequisite Tasks
3.2. Initial Setup Tasks
4. Managing GFS2
4.1. Making a File System
4.2. Mounting a File System
4.3. Unmounting a File System
4.4. Special Considerations when Mounting GFS2 File Systems
4.5. GFS2 Quota Management
4.5.1. Configuring Disk Quotas
4.5.2. Managing Disk Quotas
4.5.3. Keeping Quotas Accurate
4.5.4. Synchronizing Quotas with the quotasync Command
4.5.5. References
4.6. Growing a File System
4.7. Adding Journals to a File System
4.8. Data Journaling
4.9. Configuring atime Updates
4.9.1. Mount with relatime
4.9.2. Mount with noatime
4.10. Suspending Activity on a File System
4.11. Repairing a File System
4.12. Bind Mounts and Context-Dependent Path Names
4.13. Bind Mounts and File System Mount Order
4.14. The GFS2 Withdraw Function
5. Diagnosing and Correcting Problems with GFS2 File Systems
5.1. GFS2 File System Shows Slow Performance
5.2. GFS2 File System Hangs and Requires Reboot of One Node
5.3. GFS2 File System Hangs and Requires Reboot of All Nodes
5.4. GFS2 File System Does Not Mount on Newly-Added Cluster Node
5.5. Space Indicated as Used in Empty File System
A. GFS2 Quota Management with the gfs2_quota Command
A.1. Setting Quotas with the gfs2_quota command
A.2. Displaying Quota Limits and Usage with the gfs2_quota Command
A.3. Synchronizing Quotas with the gfs2_quota Command
A.4. Enabling/Disabling Quota Enforcement
A.5. Enabling Quota Accounting
B. Converting a File System from GFS to GFS2
B.1. Converstion of Context-Dependent Path Names
B.2. GFS to GFS2 Conversion Procedure
C. GFS2 tracepoints and the debugfs glocks File
C.1. GFS2 tracepoint Types
C.2. Tracepoints
C.3. Glocks
C.4. The glock debugfs Interface
C.5. Glock Holders
C.6. Glock tracepoints
C.7. Bmap tracepoints
C.8. Log tracepoints
C.9. References
D. Revision History
Index