Red Hat Enterprise Linux 7

Global File System 2

Red Hat Global File System 2

Steven Levine

Red Hat Customer Content Services

Abstract

This book provides information about configuring and maintaining Red Hat GFS2 (Red Hat Global File System 2) for Red Hat Enterprise Linux 7.
1. GFS2 Overview
1.1. New and Changed Features
1.1.1. New and Changed Features for Red Hat Enterprise Linux 7.0
1.1.2. New and Changed Features for Red Hat Enterprise Linux 7.1
1.1.3. New and Changed Features for Red Hat Enterprise Linux 7.2
1.2. Before Setting Up GFS2
1.3. Installing GFS2
1.4. Replacement Functions for gfs2_tool in Red Hat Enterprise Linux 7
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. VFS Tuning Options: Research and Experiment
2.5.3. SELinux: Avoid SELinux on GFS2
2.5.4. Setting Up NFS Over GFS2
2.5.5. Samba (SMB or Windows) File Serving Over GFS2
2.5.6. Configuring Virtual Machines for 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. Managing GFS2
3.1. Making a File System
3.2. Mounting a File System
3.3. Unmounting a File System
3.4. Special Considerations when Mounting GFS2 File Systems
3.5. GFS2 Quota Management
3.5.1. Configuring Disk Quotas
3.5.2. Managing Disk Quotas
3.5.3. Keeping Quotas Accurate
3.5.4. Synchronizing Quotas with the quotasync Command
3.5.5. References
3.6. Growing a File System
3.7. Adding Journals to a File System
3.8. Data Journaling
3.9. Configuring atime Updates
3.9.1. Mount with relatime
3.9.2. Mount with noatime
3.10. Suspending Activity on a File System
3.11. Repairing a File System
4. Diagnosing and Correcting Problems with GFS2 File Systems
4.1. GFS2 File System Shows Slow Performance
4.2. GFS2 File System Hangs and Requires Reboot of One Node
4.3. GFS2 File System Hangs and Requires Reboot of All Nodes
4.4. GFS2 File System Does Not Mount on Newly Added Cluster Node
4.5. Space Indicated as Used in Empty File System
5. Configuring a GFS2 File System in a Cluster
A. GFS2 Performance Analysis with Performance Co-Pilot
A.1. Overview of Performance Co-Pilot
A.2. PCP Deployment
A.3. PCP Installation
A.4. Tracing GFS2 Performance Data
A.5. Metric Configuration (using pmstore)
A.6. Logging Performance Data (using pmlogger)
A.7. Visual Tracing (using PCP-GUI and pmchart)
B. GFS2 Tracepoints and the debugfs glocks File
B.1. GFS2 Tracepoint Types
B.2. Tracepoints
B.3. Glocks
B.4. The glock debugfs Interface
B.5. Glock Holders
B.6. Glock Tracepoints
B.7. Bmap Tracepoints
B.8. Log tracepoints
B.9. Glock Statistics
B.10. References
C. Revision History
Index