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.
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.
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.
Answer y to the following prompt:
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.
Logical Volumes NAME fslv1 Number of LOGICAL PARTITIONS 64 PHYSICAL VOLUME names hdisk2 Logical volume TYPE jfs
crfs -v jfs -d fslv1 -m /u/myfs -a logname=/dev/fsvg1log mount /u/myfs
lsvg -l fsvg1
There are two logical volumes of the following types listed: