REDHAT ENTERPRISE LINUX 5 - GLOBAL FILE SYSTEM Manual

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[Page 1] Red Hat ENTERPRISE LINUX 5 - GLOBAL FILE SYSTEM

Red Hat Enterprise Linux 5 Global File System Red Hat Global File System ...

[Page 2] Red Hat ENTERPRISE LINUX 5 - GLOBAL FILE SYSTEM

Global File System Red Hat Enterprise Linux 5 Global File System Red Hat Global File System Edition 4 Copyright © 2010 Red Hat, Inc. The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share ...

[Page 3] Red Hat ENTERPRISE LINUX 5 - GLOBAL FILE SYSTEM

iii Introduction v 1. Audience ..........................................................................................

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Global File System iv Index 45 ...

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v Introduction The Global File System Configuration and Administration document provides information about configuring and maintaining Red Hat GFS (Red Hat Global File System). A GFS file system can be implemented in a standalone system or as part of...

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Introduction vi • Red Hat Cluster Suite Release Notes — Provides information about the current release of Red Hat Cluster Suite. Red Hat Cluster Suite documentation and other Red Hat documents are available in HTML, PDF, and RPM versions on the R...

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Pull-quote Conventions vii This denotes words or phrases encountered on a system, including application names; dialog box text; labeled buttons; check-box and radio button labels; menu titles and sub-menu titles. For example: Choose System → Prefer...

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Introduction viii books_tests Desktop1 downloads images notes scripts svgs Source-code listings are also set in mono-spaced roman but add syntax highlighting as follows: package org.jboss.book.jca.ex1; import javax.naming.InitialContext; pu...

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Feedback ix Bugzilla component: Documentation-cluster Book identifier: Global_File_System(EN)-5 (2010-03-11T15:10) By mentioning this manual's identifier, we know exactly which version of the guide you have. If you have a suggestion for improvin...

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Chapter 1. 1 GFS Overview The Red Hat GFS file system is a native file system that interfaces directly with the Linux kernel file system interface (VFS layer). When implemented as a cluster file system, GFS employs distributed metadata and multiple j...

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Chapter 1. GFS Overview 2 Note When you configure a GFS file system as a cluster file system, you must ensure that all nodes in the cluster have access to the shared file system. Asymmetric cluster configurations in which some nodes have access to th...

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Superior Performance and Scalability 3 Note The deployment examples in this chapter reflect basic configurations; your needs might require a combination of configurations shown in the examples. 1.2.1. Superior Performance and Scalability You can obta...

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Chapter 1. GFS Overview 4 Figure 1.2. GFS and GNBD with a SAN Figure 1.3, “GFS and GNBD with Directly Connected Storage” shows how Linux client applications can take advantage of an existing Ethernet topology to gain shared access to all block st...

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Before Setting Up GFS 5 Software Component Description gfs.ko Kernel module that implements the GFS file system and is loaded on GFS cluster nodes. lock_dlm.ko A lock module that implements DLM locking for GFS. It plugs into the lock harness, lock_ha...

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Chapter 2. 7 Getting Started This chapter describes procedures for initial setup of GFS and contains the following sections: • Section 2.1, “Prerequisite Tasks” • Section 2.2, “Initial Setup Tasks” 2.1. Prerequisite Tasks Before setting u...

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Chapter 2. Getting Started 8 mkfs -t gfs -p lock_dlm -t LockTableName -j NumberJournals BlockDevice You can use either of the following formats to create a local GFS file system: gfs_mkfs -p lock_nolock -j NumberJournals BlockDevice mkfs -t gfs -p lo...

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Chapter 3. 9 Managing GFS This chapter describes the tasks and commands for managing GFS and consists of the following sections: • Section 3.1, “Creating a File System” • Section 3.2, “Mounting a File System” • Section 3.3, “Unmountin...

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Chapter 3. Managing GFS 10 Note Once you have created a GFS file system with the gfs_mkfs command, you cannot decrease the size of the file system. You can, however, increase the size of an existing file system with the gfs_grow command, as described...

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Examples 11 NumberJournals Specifies the number of journals to be created by the gfs_mkfs command. One journal is required for each node that mounts the file system. (More journals than are needed can be specified at creation time to allow for future...

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Chapter 3. Managing GFS 12 Complete Options Table 3.1, “Command Options: gfs_mkfs” describes the gfs_mkfs command options. Flag Parameter Description -b BlockSize Sets the file system block size to BlockSize. Default block size is 4096 bytes. -D ...

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Mounting a File System 13 3.2. Mounting a File System Before you can mount a GFS file system, the file system must exist (refer to Section 3.1, “Creating a File System”), the volume where the file system exists must be activated, and the supporti...

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Chapter 3. Managing GFS 14 (for example, -r). For information about other Linux mount command options, see the Linux mount man page. Table 3.2, “GFS-Specific Mount Options” describes the available GFS-specific -o option values that can be passed ...

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Unmounting a File System 15 Option Description Note: This option is turned on automatically if lock_nolock locking is specified; however, you can override it by using the ignore_local_fs option. upgrade Upgrade the on-disk format of the file system s...

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Chapter 3. Managing GFS 16 • If a GFS file system has been mounted manually with the mount command, be sure to unmount the file system manually with the umount command before rebooting or shutting down the system. If your file system hangs while it...

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GFS Quota Management 17 logd_secs = 1 quotad_secs = 5 inoded_secs = 15 glock_purge = 0 quota_simul_sync = 64 quota_warn_period = 10 atime_quantum = 3600 quota_quantum = 60 quota_scale = 1.0000 (1, 1) quota_enforce = 1 quota_account = 1 new_files_jd...

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Chapter 3. Managing GFS 18 Usage Setting Quotas, Hard Limit gfs_quota limit -u User -l Size -f MountPoint gfs_quota limit -g Group -l Size -f MountPoint Setting Quotas, Warn Limit gfs_quota warn -u User -l Size -f MountPoint gfs_quota warn -g Group -...

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Displaying Quota Limits and Usage 19 gfs_quota get -u User -f MountPoint Displaying Quota Limits for a Group gfs_quota get -g Group -f MountPoint Displaying Entire Quota File gfs_quota list -f MountPoint User A user ID to display information about a ...

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Chapter 3. Managing GFS 20 Space allocated to GFS's hidden files can be left out of displayed values for the root UID and GID by adding the -d option to the command line. This is useful when trying to match the numbers from gfs_quota with the re...

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Disabling/Enabling Quota Enforcement 21 gfs_tool settune MountPoint quota_quantum Seconds MountPoint Specifies the GFS file system to which the actions apply. Seconds Specifies the new time period between regular quota-file synchronizations by GFS. S...

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Chapter 3. Managing GFS 22 Examples This example disables quota enforcement on file system /gfs. gfs_tool settune /gfs quota_enforce 0 This example enables quota enforcement on file system /gfs. gfs_tool settune /gfs quota_enforce 1 3.6.5. Disabling/...

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Growing a File System 23 Examples This example disables quota accounting on file system /gfs on a single node. gfs_tool settune /gfs quota_account 0 This example enables quota accounting on file system /gfs on a single node and initializes the quota ...

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Chapter 3. Managing GFS 24 • Expand the underlying cluster volume with LVM. For information on administering LVM volumes, see the LVM Administrator's Guide The gfs_grow command provides a -T (test) option that allows you to see the results of ...

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Adding Journals to a File System 25 3.8. Adding Journals to a File System The gfs_jadd command is used to add journals to a GFS file system after the device where the file system resides has been expanded. Running a gfs_jadd command on a GFS file sys...

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Chapter 3. Managing GFS 26 Local flocks = FALSE Local caching = FALSE Oopses OK = FALSE Type Total Used Free use% ------------------------------------------------------------------------ inodes ...

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Direct I/O 27 Flag Parameter Description -h Help. Displays short usage message. -J MegaBytes Specifies the size of the new journals in megabytes. Default journal size is 128 megabytes. The minimum size is 32 megabytes. To add journals of different si...

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Chapter 3. Managing GFS 28 To cause the O_DIRECT flag to be defined with recent glibc libraries, define _GNU_SOURCE at the beginning of a source file before any includes, or define it on the cc line when compiling. 3.9.2. GFS File Attribute The gfs_t...

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Data Journaling 29 Usage Setting the inherit_directio flag gfs_tool setflag inherit_directio Directory Clearing the inherit_directio flag gfs_tool clearflag inherit_directio Directory Directory Specifies the directory where the inherit_directio flag ...

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Chapter 3. Managing GFS 30 Usage Setting and Clearing the inherit_jdata Flag gfs_tool setflag inherit_jdata Directory gfs_tool clearflag inherit_jdata Directory Setting and Clearing the jdata Flag gfs_tool setflag jdata File gfs_tool clearflag jdata ...

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Mount with noatime 31 If atime updates are enabled as they are by default on GFS and other Linux file systems then every time a file is read, its inode needs to be updated. Because few applications use the information provided by atime, those updates...

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Chapter 3. Managing GFS 32 The gfs_tool settune command is used to change the atime_quantum parameter value. It must be set on each node and each time the file system is mounted. The setting is not persistent across unmounts. Usage Changing the atime...

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Displaying Extended GFS Information and Statistics 33 This example ends suspension of writes to file system /gfs. gfs_tool unfreeze /gfs 3.13. Displaying Extended GFS Information and Statistics You can use the gfs_tool command to gather a variety of ...

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Chapter 3. Managing GFS 34 3.13.2. Displaying GFS Counters You can use the counters flag of the gfs_tool to display statistics about a file system. If the -c option is used, the gfs_tool command continues to run, displaying statistics once per second...

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Displaying GFS Counters 35 log wraps The number of times journal has wrapped around. outstanding LM calls obsolete outstanding BIO calls obsolete fh2dentry misses The number of times an NFS call could not find a dentry structure in the cache. glocks ...

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Chapter 3. Managing GFS 36 block I/O writes obsolete Usage gfs_tool counters MountPoint MountPoint Specifies the file system to which the action applies. Example This example reports statistics about the file system mounted at /mnt/gfs. [root@tng3-1 ...

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Displaying Extended Status 37 Note The information that the gfs_tool stat command displays reflects internal file system information. This information is intended for development purposes only. Usage gfs_tool stat File File Specifies the file from wh...

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Chapter 3. Managing GFS 38 3.14. Repairing a File System When nodes fail with the file system mounted, file system journaling allows fast recovery. However, if a storage device loses power or is physically disconnected, file system corruption may occ...

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Example 39 gfs_fsck -y BlockDevice -y The -y flag causes all questions to be answered with yes. With the -y flag specified, the gfs_fsck command does not prompt you for an answer before making changes. BlockDevice Specifies the block device where the...

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Chapter 3. Managing GFS 40 Syncing the device. Freeing buffers. 3.15. Context-Dependent Path Names Context-Dependent Path Names (CDPNs) allow symbolic links to be created that point to variable destination files or directories. The variables are reso...

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Example 41 Variable Description @os This variable resolves to a real file or directory named with the operating-system name string produced by the output of the following command: echo `uname -s` @sys This variable resolves to a real file or director...

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Chapter 3. Managing GFS 42 perform file system recovery with the gfs_fsck command. The GFS withdraw function is less severe than a kernel panic, which would cause another node to fence the node. An example of an inconsistency that would yield a GFS w...

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43 Appendix A. Revision History Revision 5.5-1 Thu Mar 18 2010 Steven Levine [email protected] Resolves: #568179 Adds note clarifying support policy for single-node system. Resolves: #562199 Adds note clairfying 16-node limitation. Resolves: #515348...

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44 ...

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45 Index A adding journals to a file system, 25 atime, configuring updates, 30 mounting with noatime, 31 tuning atime quantum, 31 audience, v C CDPN variable values table, 40 configuration, before, 5 configuration, initial, 7 prerequisite tasks, 7 cr...

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Index 46 O overview, 1 configuration, before, 5 economy, 2 features, new and changed, 2 GFS software components, 4 performance, 2 scalability, 2 P parameters, GFS tunable, 16 path names, context-dependent (CDPNs), 40 preface (see introduction) prereq...