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 4MB. 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. See "Resource Requirements of Diskless Workstations" in AIX Versions 3.2 and 4 Performance Tuning Guide for more details.
You can use the Web-based System Manager fast path wsm 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 will be the dedicated device for the file system log. The log will be on hdisk1 and the file system will be on hdisk2 (a 256MB 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.
smit mkvg
smit mklv
Logical Volumes NAME fsvg1log Number of LOGICAL PARTITIONS 1 PHYSICAL VOLUME names hdisk1 Logical volume TYPE jfslog POSITION on Physical Volume centerAfter you set the fields, press Enter.
/usr/sbin/logform /dev/fsvg1logAnswer y to the following prompt:
Destroy /dev/fsvg1logand 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.
smit mklv
Logical Volumes NAME fslv1 Number of LOGICAL PARTITIONS 64 PHYSICAL VOLUME names hdisk2 Logical volume TYPE jfsPress Enter.
crfs -v jfs -d fslv1 -m /u/myfs -a logname=/dev/fsvg1log mount /u/myfs
lsvg -l fsvg1There should be two logical volumes of the following types listed:
/dev/fsvg1log jfslogthen:
fslv1 jfs