Creating new logical volume

[Asad Malik]

Hi
system is HP 9000 D370 running 11.0
i have to create two new logical volumes on an existing volume group. free space is available on that volume group. Can i do this on a production system without impacting applications and users (on the fly as they say)or what precautions i have to take,
like do i have to deactivate a volume group or unmount existing filesystems on that volume group, or reboot the system . does the creation will have any impact on the existing filesystems on that volume group,
Secondly can we remove the filesystems and logical volumes from the volume group while the system is running live applications and fully in production.

Thanks

[Brian M. Fisher]

You can add logical volumes "on the fly". In order to remove a volume group, the file systems must be unmounted so no users can be actively using them.

Brian
<*(((>< er

[Antoanetta Naghiu · Accepted solution]

Asad,
1.If you have free space in the vg, you can go and create a new lv, newfs on it, mount it with no problem in the fly. No ipact in the production machine.
2.If you want to free up space, just unount the fs, and, again, in the fly you can delete the lv. To reduce a lv on the fly you need Advanced JFS.
Hope this helps.

[Tim Malnati]

Just an added thought... If you want to keep future maintenance 'on the fly' as well, configure the logical volume using VxFS. The Advanced JFS product allows all sorts of maintenance action (increase/decrease size, defraging) while users are active in the file system. HFS requires unmounting the volume to perform maintenance, so should probably be avoided.

[Rick Garland]

The making of additional LVs will not impact a production environment, except to add more space. The LV has not been created as of yet and the system isn't using. Can do the lvcreate and lvextend commands (HFS or VXFS) without having to deactivate the VG. Once created, be sure to make corresponding entry in /etc/fstab so the filesystem will be mounted on boot.

[Alan Riggs]

Just adding my voice to the chorus,

Creation of new lvols/filesystems may be done on thefly with no appreciable system impact. Further filesystem and lvol maintenance can also be performed on the fly *if* you have the optional Online JFS product. Otherwise, the filesystem you work on will need to be unmounted (but no other systems need be affected).

[Adrian Voysey]

Hi,

A thing to consider when creating your filesystems is , specify the disks on which you want to create your filesystem i.e. have a look on the system , check the disks which are not frequently used ( i.e. write a lot of data to ) and use those disks if you don't specify the disks then lvm will create your LV by selecting the disk with the most amount of disk space.
Also make sure you don;t use the same LV name which is currently used ( i know something simple , hey check it any way)

Regarding filesystems , yes you can remove filesystems but depends on what they are i.e.
if user filesystems then you can remove but check if the are nfs mounted or not , System filesystems do not remove i.e. / usr /tmp /var etc..

cheers

[Vincente Fernandes]

Just to add a few more thoughts. LV creation can be done in 2 ways. Assuming you have installed JFS.
1. Commad line: If your are very much comforatable with it and make sure that you update "/etc/fstab" otherwise the file system won't mount next time after reboot.
2. SAM: Since it is menu driven, it helps a lot when one is not an expert user and it updates all the necessary files. It also gives all the details about current VG & LV which is very usefull for new admins.