Red Hat GFS is a cluster file system that provides data sharing among Linux-based computers. GFS provides a single, consistent view of the file system name space across all nodes in a cluster. It allows applications to install and run without much knowledge of the underlying storage infrastructure. GFS is fully compliant with the IEEE POSIX interface, allowing applications to perform file operations as if they were running on a local file system. Also, GFS provides features that are typically required in enterprise environments, such as quotas, multiple journals, and multipath support.
GFS provides a versatile method of networking your storage according to the performance, scalability, and economic needs of your storage environment.
This chapter provides some very basic, abbreviated information as background to help you understand GFS. It contains the following sections:
This section lists new and changed features included with the initial release of Red Hat GFS 6.0 and Red Hat GFS 6.0 for Red Hat Enterprise Linux 3 Update 5.
New and Changed Features with the Initial Release of Red Hat GFS 6.0
File access control lists (ACLs) and extended file attributes in GFS file systems — This release adds the capability of setting and getting file ACLs and extended file attributes in a GFS file system. The Linux commands setfacl and getfacl set and get ACLs. The Linux commands setfattr and getfattr set and get file attributes. In addition, this release adds a GFS-specific mount command option, -o acl. The new option allows users to set ACLs. For more information about the -o acl option, refer to Section 9.2 Mounting a File System.
Additional fencing agents — This release adds fencing agents for McData Fibre Channel (FC) switches, Egenera BladeFrame systems, and xCAT (Extreme Cluster Administration Toolkit) clusters.
Initialization scripts — This release adds init.d scripts for the pool, ccsd, lock_gulmd, and gfs modules. For more information about the scripts, refer to Chapter 12 Using GFS init.d Scripts.
Configurable node-failure detection parameters — This release adds optional parameters for setting heartbeat rate and allowed misses. Together, the parameters determine the time interval allowed without response from a node before the node is considered to have failed. For more information, refer to Section 6.5 Creating the cluster.ccs File.
Removal of license mechanism — Previous GFS releases required a license file that defined the term of use and which GFS features were enabled. This release does not require a license file.
Initial-configuration druid via Red Hat Cluster Suite — When GFS is installed with Red Hat Cluster Suite, a configuration druid is available with Cluster Suite for initial configuration of GFS. For more information about the druid, refer to the Cluster Suite documentation.
New and Changed Features with Red Hat GFS 6.0 for Red Hat Enterprise Linux 3 Update 5
Enhanced gfs_fsck performance and changes to the gfs_fsck command — The gfs_fsck function performs 10 times as fast as gfs_fsck in releases earlier than Red Hat GFS 6.0 for Red Hat Enterprise Linux 3 Update 5. In addition, the enhanced gfs_fsck function includes changes to certain command options. For more information about changes to the command options, refer to Section 9.12 Repairing a File System.
Optional usedev key available for use with the nodes.ccs file (nodes.ccs:nodes) — The value of the usedev key is a named device from the ip_interfaces section. If usedev is present, GULM uses the IP address from that device in the ip_interfaces section. Otherwise GULM uses the IP address from libresolv, as it does in releases earlier than Red Hat GFS 6.0 for Red Hat Enterprise Linux 3 Update 5. For more information about the usedev key, refer to Section 6.7 Creating the nodes.ccs File
For information about using GFS with Red Hat Cluster Suite, refer to Appendix A Using Red Hat GFS with Red Hat Cluster Suite. For GFS upgrade instructions, refer to Appendix B Upgrading GFS.