Home > Veritas Storage Foundation™ Volume Manager Manual Pages

VXDMPROOT (1M)

Maintenance Commands

NAME
SYNOPSIS
DESCRIPTION
NAME
vxdmproot - administer support of LVM bootability over DMP

SYNOPSIS
/usr/sbin/vxdmproot add dmp_node | subpath
/usr/sbin/vxdmproot install
/usr/sbin/vxdmproot remove dmp_node | subpath
/usr/sbin/vxdmproot uninstall

DESCRIPTION
The AIX Logical Volume Manager (LVM) is not capable of switching between multiple paths that may exist to the boot disk. If the path that it selects becomes unavailable at boot time, the root file system is disabled, and the boot fails. The Dynamic Multipathing (DMP) feature of Veritas Volume Manager can be configured to overcome this problem by ensuring that an alternate path is available at boot time.
Support for LVM bootability over DMP is enabled or disabled by running vxdmproot command with the install and uninstall keywords. Individual DMP nodes or subpaths can be added or removed from those supported by using the command with the add and remove keywords, and specifying a DMP node name or operating system native device name as an argument.
LVM bootability over DMP can be verified as being enabled on a system if the following command shows the same major number for the DMP driver and for the boot disk:
```
ls -l /dev/`bootinfo -b` /dev/vx/dmpconfig
```
Migrating an internal root disk to a SAN root disk under DMP control
If the system has been booted from an internal disk (such as hdisk0), an alternate root disk can be configured on the attached SAN storage before putting it under DMP control.
To migrate a root disk from LVM to DMP control:
1.
Use the chdev command to clear the physical volume identifier (PVID) of the disk in the SAN storage that is to be the SAN root disk:
```
chdev -l hdisk373 -a pv=clear
```
If the SAN disk is already multipathed by DMP, this command needs to be run for all of the paths to the disk.
2.
Use the alt_disk_install command to create the SAN root disk:
```
alt_disk_install -C hdisk373
```
3.

Reboot the system from the SAN root disk.
To configure DMP, follow the steps in "Configuring DMP support for booting over a SAN."

Migrating a SAN root disk to DMP control
If the system has been booted from a SAN disk under MPIO control, MPIO must be disabled before DMP control can be enabled.
To migrate a SAN root disk from MPIO to DMP control:

1.

Disable MPIO by installing a device-specific ODM definition package as described in the following TechNote:
http://library.veritas.com/docs/263558

2.

Reboot the system. The system is booted without any multipathing support.

3.

To configure DMP, follow the steps in "Configuring DMP support for booting over a SAN."

Configuring DMP support for booting over a SAN
Configuring DMP to work with a LVM root disk over a SAN requires that the system is correctly configured to use the boot device over all possible paths.
To configure DMP support for booting over a SAN:
1.
If the LVM root disk is multipathed with 4 paths, the output from the lspv command output for the root volume group (rootvg) is similar to the following:
```
# lspv | grep rootvg
hdisk374	00cbf5ce56def54d 	rootvg	active
hdisk375	00cbf5ce56def54d 	rootvg
hdisk376	00cbf5ce56def54d 	rootvg
hdisk377	00cbf5ce56def54d 	rootvg
```
The PVID and volume group entries in the second and third columns should be identical for all the paths.
2.
If the PVID and volume group entries are not set correctly on one or more of the paths, use the chdev command to set the correct value, as shown in this example:
```
# chdev -l hdisk377 -a pv=yes
hdisk377 changed
```
3.
Check that the output from the bootlist command is correct:
```
# bootlist -m normal -o
hdisk374 blv=hd5
hdisk375 blv=hd5
hdisk376 blv=hd5
hdisk377 blv=hd5
```
In this example, the default boot volume, hd5, should be shown for each path.
4.
If the blv option is not set for a path to the disk, use the bootlist command to set it:
```
bootlist -m normal hdisk377 blv=hd5
```
5.
Run the vxdmproot command to configure DMP on the root disk:
```
vxdmproot install
```
6.

Reboot the system. DMP takes control of the SAN boot device in order to perform load balancing and failover.

7.
To check whether DMP is controlling the SAN root disk, verify that the major numbers of the DMP driver and the boot disk are the same:
```
# ls -l /dev/`bootinfo -b` /dev/vx/dmpconfig
brw------- 1 root system 42,  1 Sep 07 16:16 /dev/hdisk374
crw------- 1 root system 42,65535 Nov 24 14:25 /dev/vx/dmpconfig
```
KEYWORDS

add

Adds support for LVM bootability over DMP for all subpaths of the specified boot disk. The argument can either be the name of the parent DMP node, or the operating system native device name of the boot disk.

install

Enables support for LVM bootability over DMP for the current boot disk and all of its subpaths. This allows the system to be booted from any of these subpaths.

remove

Removes support for LVM bootability over DMP for all subpaths of the specified boot disk. The argument can either be the name of the parent DMP node, or the operating system native device name of the boot disk.

uninstall

Disables support for LVM bootability over DMP for the current boot disk and all of its subpaths.

NOTES
The LVM bootability over DMP feature currently does not support operations on:
- Root volume groups that span multiple disks. In this case, DMP is enabled only on the disk which has the boot volume, and not for any other disks in the root volume group.
- LVM boot disk mirrors
- Disk arrays other than A/A arrays.
To avoid data corruption that may render your system unbootable, disable the LVM bootability over DMP feature before performing any operation (for example, Dynamic Reconfiguration (DR)) that shuffles device numbers or device names. The LVM bootability over DMP feature can be re-enabled after completing the reconfiguration and rebooting the system.
If a reconfiguration is performed while the LVM bootability over DMP feature is enabled, use the following commands to reconfigure DMP before the system is next rebooted:
```
cfgmgr
vxdmproot install
```
If the LVM bootability over DMP feature cannot be enabled by executing vxdmproot install or vxdmproot add, this may be because the file that corresponds to the subpath from which the system has been bootstrapped may be corrupted or the corresponding key is invalid. To correct the problem, remove the directory /etc/vx/lvm-boot and the file /usr/lib/boot/protoext/disk.proto.ext.vxvm.disk.rte, and run the command again.
If the LVM bootability over DMP feature cannot be disabled by executing vxdmproot uninstall or vxdmproot remove, this may be because the bosboot command has failed for some reason, and vxdmproot cannot clean up the ODM database entries. To correct the problem, remove the directory /etc/vx/lvm-boot and the file /usr/lib/boot/protoext/disk.proto.ext.vxvm.disk.rte, and run the command again.
The vxdmproot add and remove commands cannot be used with boot disks that do not belong to an imported volume group. This is due to a limitation, which does not allow you to write to external disks that do not belong to an imported volume group. The workaround is to boot from the disk, and then run vxdmproot install or vxdmproot uninstall to enable or disable the LVM bootability over DMP feature.

SEE ALSO
alt_disk_install(1), bootinfo(1), bootlist(1), bosboot(1), chdev(1), lspv(1), vxdmpadm(1M)
Last updated: 1 June 2005
Copyright ©2009 Symantec Corporation
All rights reserved.

VXDMPROOT (1M)

Table of contents