C.3 Viewing Free Space Available to EVMS-Managed Devices

When creating an NSS pool on Linux, you can use free space only from devices managed by EVMS. If you use multiple volume managers, make sure that the devices you select for the pool are already managed by EVMS, or they are free unpartitioned devices. After you select free space from an unpartitioned device, NSS automatically sets up the device to be managed by EVMS.

The OES 2 Linux install uses LVM2 by default as the volume manager of the system device, but NSS requires EVMS. The Linux 2.6 kernel prevents multiple volume managers from managing the same device. If you use LVM2 and EVMS to manage different devices on the server, EVMS might display free space on the LVM-managed devices that EVMS cannot actually manage.

To avoid confusion, you can prevent display of space that is unavailable to EVMS. Edit the /etc/evms.conf file to add the device to the exclude list of the sysfs_devices section.

For example, in a typical OES 2 Linux install, the sda device contains the boot device and the root volume. Unless you have previously made EVMS the volume manager for that device, it is managed by LVM2 and cannot be used to create NSS pools. To prevent the display of space from sda, edit the /etc/evms.conf file as follows:

sysfs_devices {
exclude = [sda]

To exclude multiple devices (such as /dev/sda and /dev/sdb), use the following format:

exclude = [sda sdb]