VERITAS Volume Manager 4.1 Administrator's Guide

Chapter 2 75

Removing Disks from the DISKS Category

To remove disks from the DISKS (JBOD) category, use the vxddladm command with the

rmjbod keyword. The following example illustrates the command for removing disks supplied

by the vendor, Seagate:

# vxddladm rmjbod vid=SEAGATE

Adding Foreign Devices

DDL cannot discover some devices that are controlled by third-party drivers, such as for EMC

PowerPath and RAM disks. For these devices it may be preferable to use the multipathing

capability that is provided by the third-party drivers for some arrays rather than using the

Dynamic Multipathing (DMP) feature. Such foreign devices can be made available as simple

disks to VxVM by using the vxddladm addforeign command. This also has the effect of

bypassing DMP for handling I/O. The following example shows how to add entries for block

and character devices in the speciﬁed directories:

# vxddladm addforeign blockdir=/dev/foo/dsk chardir=/dev/foo/rdsk

By default, this command suppresses any entries for matching devices in the OS-maintained

device tree that are found by the autodiscovery mechanism. You can override this behavior by

using the -f and -n options as described on the vxddladm(1M) manual page.

After adding entries for the foreign devices, use either the vxdisk scandisks or the vxdctl

enable command to discover the devices as simple disks. These disks then behave in the same

way as autoconﬁgured disks.

The foreign device mechanism was introduced in VxVM 4.0 to support non-standard devices

such as ramdisks, some solid state disks, and pseudo-devices such as EMC PowerPath. This

mechanism has a number of limitations:

• A foreign device is always considered as simple disk with a single path. Unlike an

autodiscovered disk, it does not have a DMP node.

• It is not supported for shared disk groups in a clustered environment. Only standalone

host systems are supported.

• It is not supported for Persistent Group Reservation (PGR) operations.

• It is not under the control of DMP, so enabling of a failed disk cannot be automatic, and

DMP administrative commands are not applicable.

• Enclosure information is not available to VxVM. This can reduce the availability of any

disk groups that are created using such devices.

If a suitable ASL is available for an array, these limitations are removed, as described in

“Third-Party Driver Coexistence” on page 65.