Commands Reference, Volume 3

logform Command

Purpose

Initializes a logical volume for use as a JFS or JFS2 log.

Description

Attention: Executing the logform command on any Journaled File System (JFS) or Enhanced Journaled File System (JFS2) log device can result in data loss and file system corruption for all JFS or JFS2 file systems logged by the log device.

The logform command initializes a logical volume for use as a JFS or JFS2 log device. The logform command destroys all log records on existing log devices, which may result in file system data loss.

The Logname parameter specifies the absolute path to the logical volume to be initialized (for example, /dev/jfslog1).

Note: The only intended use for the logform command is to initialize a JFS log logical volume as a JFS log device or to initialize a JFS2 log logical volume as a JFS2 log device. The SMIT interface for creating a JFS or JFS2 and the crfs command allow only one JFS or JFS2 log device per volume group.

Implementation Specifics

JFS is a POWER-based platform only, and JFS2 is common to both platforms.

Flag

-V vfstype

If specified, vfstype indicates what type of file system the log should be formatted for. If this option is not specified, then the type is obtained from the logical volume's type. If there is no type specified for the logical volume, then the default vfs type from /etc/vfs is used.

Examples

To create a JFS logging device on a newly created volume group, first create a logical volume of type jfslog:
```
mklv -t jfslog -y jfslog1 newvg 1
```
This command creates a jfslog logical volume named jfslog1 in the volume group newvg. The size of the logical volume is 1 logical partition.
To format the jfslog1 logical volume once it has been created, enter:
```
logform /dev/jfslog1
```
The jfslog1 logical volume is now ready to be used as a JFS log device.

Files

/etc/filesystems

Lists the known file systems and defines their characteristics, including the log device.

Related Information

The crfs command, mkfs command, mklv command.

The File System Overview for System Management in AIX 5L Version 5.1 System Management Concepts: Operating System and Devices explains file system types, management, structure, and maintenance.

The Mounting Overview in AIX 5L Version 5.1 System Management Concepts: Operating System and Devices explains mounting files and directories, mount points, and automatic mounts.

The Understanding Journaled File System Size Limitations in AIX 5L Version 5.1 System Management Concepts: Operating System and Devices