Rule of Thumb for JFSLOG Size 1

[riscman]

I am creating scripts to to create volume groups, logical volumes, etc. I know that there should be one jfslog logical volume per volume group and it is one physical partition in size by default.

What is the rule of thumb for sizing a jfslog logical volume?

Thanks in advance,

Jack

 

[AIX5L]

Hi riscman

1 Mb Logsize = 2Gb FS-Size are OK.

When you create an new one, then do this with the logform Command.

logform /dev/newloglv Formats LV as jfslog
chfs -a log=/dev/newloglv /fsys
fsck -y /fsys
getlvcb -AT LV

 

[aixqueen]

Journaled File System Log Size Issues

Another size-related issue is the size of the JFS log. In most instances, multiple
journaled file systems use a common log configured to be 4MB in size. For example,
after initial installation, all file systems within the root volume group use logical
volume hd8 as a common JFS log. The default logical volume partition size is
4MB, and the default log size is one partition, therefore, the root volume group
normally contains a 4MB JFS log. When file systems exceed 2GB or when the total
amount of file system space using a single log exceeds 2GB, the default log
size may not be sufficient. In either case, the log sizes should be scaled upward
as the file system size increases.The JFS log is limited to a maximum size of 256MB.


How do I set up a new jfslog?

Unmount the filesystem before you try to point the log to the new filesystem.
If a JFS log does not already exist on the new
volume group, then create one by using the 'mklv'
and 'logform' commands.

OR DO IN SMIT calling it jfslog for type............ but choosing
one of the disks that the filesystem is on......... smitty , then physical and logical
storage, logical volume manager. Logical volumes, add a logical volume
Add a Logical Volume

Type or select values in entry fields.
Press Enter AFTER making all desired changes.

Logical volume NAME []
(you can leave blank)
* VOLUME GROUP name [datavg]
(fill in your volume group with f4)
* Number of LOGICAL PARTITIONS [1] #
( one or two depending on pp size)
PHYSICAL VOLUME names [hdisk5]
(actually choose the volume name with the f4)
Logical volume TYPE [jfslog ]
(jfslog is the type)
POSITION on physical volume middle []+
RANGE of physical volumes minimum []+
MAXIMUM NUMBER of PHYSICAL VOLUMES [] #
Number of COPIES of each logical
partition [1] +
Mirror Write Consistency? [yes] +
Allocate each logical partition copy [yes] +

For example:

mklv -t jfslog -y datavg 1
(where "datavg" is the name of the users volume group.)
This will return a new JFS log lv such as "loglv01" then run logform on it.

logform loglv01

Change the file system to reference the new log device with the 'chfs' command.

For example:

chfs -a log=/dev/loglv01 /myfilesystem
(where "myfilesystem" is the name of the users file system.)
(you can then check in the /etc/filesystem file to be sure it has been changed) and
also do a savebase from the command line.

You can fsck the unmounted filesystem to be sure all is correct...........

Mount the file system

For example:

mount /myfilesystem
(where "myfilesystem" is the name of the users file system.)

 

[riscman]

Thanks AIXQUEEN and AIX5L. You both have been most helpful.



Cheers,

Jack