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Integrity Virtual Machines and Dynamic Root Expansion

Abstract

Dynamic Lun Expansion is not supported

Contents


Design Limitations

Section 7.2.1.5 of the HP-VM Manual is very clear on the topic:

7.2.1.5 VM Storage Changes
Depending on how you set up storage for a virtual machine, the resulting configuration can be more or less difficult to change.
The ability to change virtual media depends on the type of virtual media used. Whole disks are not normally adjustable in terms of size, but some high-end storage enclosures might permit the adjustment of a LUN without losing that LUN's data. Logical volumes are adjustable without losing any data. Finally, files can be changed easily with VM Host file system commands.
No changes to any virtual media can take place on the VM Host until the virtual device that uses the media is removed from the active VM. Attempts to change virtual devices that have I/O active on them is denied by the hpvmmodify command. Once an active virtual machine is allocated virtual media for a virtual device, that virtual machine owns that media and can access it any time. VM Host administrators need to coordinate with VM guest administrators about active virtual machine changes, if the two roles are served by different individuals.
This coordination might also be necessary for attached I/O devices. Once a VM Host device is attached to the virtual machine, it is controlled and owned by that virtual machine. Modifications to the attached device, like changing a tape, can be done physically without detaching the device from the guest. However, such changes might need to be coordinated with the VM Host administrator, especially if the guest administrator has no physical access to the device attached to the virtual machine.
All types of virtual storage devices can be added and removed dynamically from virtual machines. That is, virtual disks, virtual DVDs, tapes, media changers, and CD/DVD burners are all hot-swappable. However, the virtual storage adapters are currently not hot-swappable. Therefore, if all the virtual storage adapters are full, you must reboot the virtual machine when you add additional devices.

You are trying to do is what we call Dynamic Lun Expansion in the context of LVM volume manager. Trying to keep a somewhat complex topic simple, HPVM Guests don't support live changes of the size of the backing storage assigned to them.

The backing storage must be removed from the Guest and added back for the Guest to recognize the new logical volume size (1.5 TB).

The good part is that your HPVM guest LVM configuration is made to support single physical volumes, in this case the HPVM host logical volume /dev/vgvm01_data/lvvm01_data up to 63984 X 128 = 8189952 (around 7.8 TB). The value is obtained from the formula Max PE per PV X PE Size (Mbytes). You will not need to use the most complex parameters of the vgmodify command.

Still, the HPVM guest /dev/vg01 volume group is configured with a physical volume /dev/dsk/c0t1d0 of 3998 Physical Extents (Total PE). If you want to follow this direction, you will need to use the vgmodify command to increase the size the LVM header metadata. This command required that the volume group is inactive. After that, you can extend the logical volume and proceed to extend the file system.

There are three ways to acomplish this task. I'm going the layout the basic command you will need for each approach, from the simpler method to the most complex.

Section 2

Section 3

Reference

Authors

This page was last modified on 24 July 2010, at 23:41. This page has been accessed 1,887 times.