System Management Guide: Operating System and Devices

Creating a File System Log on a Dedicated Disk for a User-Defined Volume Group

A file system log is a formatted list of file system transaction records. The log for this system is called the JFS log (journaled file system log) and is used in case the system goes down before the transactions have been completed. The JFS log ensures file system integrity but not necessarily data integrity. A dedicated disk is created on hd8 for rootvg when the system is installed. The JFS log size is 4 MB. You can also create a JFS log on a separate disk for other volume groups, as shown in the following procedure. You might want to do this to improve performance under certain conditions, for example, if you have an NFS server and you want the transactions for this server to be processed without competition from other processes.

Prerequisites

Logical Volume Storage Overview in AIX 5L Version 5.1 System Management Concepts: Operating System and Devices
Developing a Logical Volume Strategy in AIX 5L Version 5.1 System Management Concepts: Operating System and Devices

Procedure

You can use Web-based System Manager (type wsm, then select lvm) instead of the following procedure. If you use the following procedure, a volume group (fsvg1) is created, with two physical volumes, one of which is the dedicated device for the file system log. The log is on hdisk1 and the file system is on hdisk2 (a 256 MB file system mounted at /u/myfs).

Note: You can place little-used programs, for example, /blv, on this physical volume without impacting performance. It is not required that it be empty except for the JFS log.

Add a new volume group (in this example, fsvg1 is the new volume group name). Type the SMIT fast path:
```
smit mkvg
```
Select the volume group name you created using. Type the SMIT fast path:
```
smit mklv
```

On the Add a Logical Volume dialog screen, set the following fields with your data. For example:

Logical Volumes NAME
fsvg1log
 
Number of LOGICAL PARTITIONS             1
 
PHYSICAL VOLUME names                    hdisk1
 
Logical volume TYPE                      jfslog
 
POSITION on Physical Volume              center

After you set the fields, press Enter.

Exit SMIT and type the following on a command line:
```
/usr/sbin/logform /dev/fsvg1log
```
Answer y to the following prompt:
```
Destroy /dev/fsvg1log
```
and press Enter.

Note: The preceding command formats the JFS-log logical volume so that it can record file-system transactions. Nothing is destroyed despite the wording in the prompt.
Type the following SMIT fast path:
```
smit mklv
```

Type the name of the new volume group (fsvg1 in this example). In the Logical Volumes dialog screen, fill in the following fields with your data. For example:

Logical Volumes NAME
fslv1
 
Number of LOGICAL PARTITIONS             64
 
PHYSICAL VOLUME names                    hdisk2
 
Logical volume TYPE                      jfs

Press Enter.

Exit SMIT and type the following on the command line:

crfs -v jfs -d fslv1 -m /u/myfs -a
logname=/dev/fsvg1log
 
mount /u/myfs

To verify that you have set up the file system and log correctly, type the following command:
```
lsvg -l fsvg1
```
There are two logical volumes of the following types listed:
```
/dev/fsvg1log   jfslog
```
then type:
```
fslv1      jfs
```