I look at my /etc/filesystems and see these stanzas
/SUM:
dev = /dev/lv_sum
vfs = jfs2
log = /dev/loglv00
mount = true
options = rw
account = false
/var:
dev = /dev/hd9var
vfs = jfs2
log = /dev/hd8
mount = automatic
check = false
type = bootfs
vol = /var
free = false
quota = no
As I know, mount = true means the mountpoint will be mounted at boot time, and false mean opposite to true. But what is the meaning of automatic here? The same with true?
Assuming I have created a new volume and mount it manually to somewhere. If I want to add it to /etc/filesystem, which log I will specify like below
/dev/loglv00
is it mandatory for all the volumes? In case the NFS do we need this?
As observed in my environment, the NFS is added to /etc/filesystems without log volume.
You will not need it for NFS filesystems and if you need it for logical filesystems you did already do something wrong - but let us start at the beginning:
JFS and JFS2 are - as the name suggests, journaling filesystems. They work (remotely) similar to a database, where every operation is stored in a "redo log" so that it can be rolled backwards (or, using the log, rolled forward). This means that JFS and JFS2 filesystems need a place where to put this log (or "journal").
JFS (or JFSv1) was used in AIX up to v5 (? IIRC) as the default. It used a separate log LV and in every volume group, along with the first LV created, such a log LV was created automatically. There is (per default) always one log LV per VG and it is always 1 PP in size.
Newer versions of AIX use JFS2, the successor of JFS, per default (it is still possible to use JFSv1, but since there is no gain in that it is highly recommended not to do so if possible) and JFS2 works - in this regard - exactly the same as JFS. Again, a log LV is created automatically. But JFS2 offers the possibility to use "inline logs" instead of the default external log and since this is much faster and also more secure (if the log LV is missing for some reason you might have troubles using an FS that utilizes it) it is recommended to use inline logs whereever possible.
If you only create FSes with inline logs the log LV will not be created at all in a VG. Therefore, if you have already a log LV in your VG this tells me that you have created FSes using the default external log instead of the inline log. If you have the possibility, recreate the FSes and with inline logs.
automatic
Automatically mounts a file system when the system is started. Unlike the true value, filesystems which are mounted with the automatic value are not mounted with the mount all command or unmounted with the unmount all command. By default, the '/', '/usr', '/var', and '/tmp' filesystems use the automatic value.
Still not clear with automatic. So how come it mounted and unmounted? I think automatic only uses for system and we should not touch. And other file systems is manipulated by us with true/false.
