1.4. Before Setting Up GFS

1.4. Before Setting Up GFS

Before you install and set up GFS, note the following key characteristics of your GFS file systems:

GFS nodes

Determine which nodes in the Red Hat Cluster Suite will mount the GFS file systems.

Number of file systems

Determine how many GFS file systems to create initially. (More file systems can be added later.)

File system name

Determine a unique name for each file system. Each file system name is required in the form of a parameter variable. For example, this book uses file system names mydata1 and mydata2 in some example procedures.

File system size

GFS is based on a 64-bit architecture, which can theoretically accommodate an 8 EB file system. However, the current supported maximum size of a GFS file system is 25 TB. If your system requires GFS file systems larger than 25 TB, contact your Red Hat service representative.

When determining the size of your file system, you should consider your recovery needs. Running the fsck command on a very large file system can take a long time and consume a large amount of memory. Additionally, in the event of a disk or disk-subsytem failure, recovery time is limited by the speed of your backup media.

Journals

Determine the number of journals for your GFS file systems. One journal is required for each node that mounts a GFS file system. Make sure to account for additional journals needed for future expansion, as you cannot add journals dynamically to a GFS file system.

GNBD server nodes

If you are using GNBD, determine how many GNBD server nodes are needed. Note the hostname and IP address of each GNBD server node for setting up GNBD clients later. For information on using GNBD with GFS, see the Using GNBD with Global File System document.

Storage devices and partitions

Determine the storage devices and partitions to be used for creating logical volumes (via CLVM) in the file systems.


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