VERITAS Volume Manager 4.1 Migration Guide

Converting LVM to VxVM

Converting LVM Volume Groups to VxVM Disk Groups

Chapter 24

In the conversion of LVM to VxVM, the areas of the disks used to store LVM metadata are

overwritten with VxVM metadata. If the VxVM metadata that needs to be written will not ﬁt

the space occupied by the LVM metadata, the group containing the disk cannot be converted.

If you have just enough space for the conversion, you probably would want to have more space

for future conﬁguration changes.

NOTE The most likely scenario in which a Volume Group cannot be converted,

because of insufﬁcient private space, is when a large Hp-UX system using

"Extent based Striping" is being used.

• A volume group containing the root volume.

vxvmconvert does not convert any volume group that contains a rootable volume, identiﬁed by

the presence of the LIF area as created by mkboot (1M). Not only is the current root volume

off limits, but any volume that might be used as an alternate root volume is rejected as well.

NOTE You can use the vxcp_lvmroot (1M) command to create a VxVM root disk on a

spare physical disk from the contents of the existing LVM root disk. Similarly,

you can use the vxres_lvmroot (1M) command to recreate an LVM root disk on a

spare disk from the contents of the VxVM root disk. For more information, see

"Rootability" in the "Administering Disks" chapter of the VERITAS Volume

Manager Administrator's Guide.

• A volume group containing mirrors using the Mirror Write Cache feature for volume

consistency recovery.

Users should be aware that when converting mirrored LVM volumes to VxVM, some of

these volumes will likely have the Mirror Write Cache consistency recovery method in

force on the volume. The vxvmconvert utility can convert these volumes, but must use the

Dirty Region Logging (DRL) feature to obtain the same level of functionality. However,

since Dirty Region Logging requires some user space to be available for the log, a

conversion could fail due to an MWC volume being full, leaving no space for the DRL log.

However it is very unlikely that this situation would occur. Note that the MWC and DRL

are used only when the system

• A volume group containing the /usr ﬁle system.

For this release, a volume group containing the /usr ﬁle system cannot be converted

because vxvmconvert needs access to ﬁles in /usr.

• Volume groups with any dump or primary swap volumes.