VERITAS Volume Manager 3.1 Migration Guide

Converting LVM to VxVM
Converting LVM Volume Groups to VxVM Disk Groups
Chapter 2 27
Volume Group Conversion Limitations
There are certain LVM volume configurations that cannot be converted
to VxVM. Some of the reasons a conversion could fail are:
• A volume group with insufficient space for metadata.
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.
• 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.
• 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. Note that
the MWC and DRL are used only when the system crashes or is
improperly shut down, to quickly bring all mirrors in the volume back
into a consistent state.
• 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.
vxvmconvert will not convert any volume group with dump or