VERITAS Volume Manager 3.5 Migration Guide (September 2004)

Chapter 2
Converting LVM to VxVM
Converting LVM Volume Groups to VxVM Disk Groups
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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 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 primary swap volumes. These are volumes
known to the boot process. However, swap volumes on volumes other than the root volume can be
converted (as long as this volume is not in the same volume group as the root volume).
• Volume group disks used in MC/ServiceGuard clusters.
The conversion process does not support conversion of any volume group that is marked as a member of a
MC/ServiceGuard or OPS Edition high availability cluster. The volume group must be deactivated and
removed from membership in the high availability cluster before it can be converted.
• Volume groups used for cluster lock disks.
The conversion process does not support conversion of a volume group that contains a disk that is being
used for a cluster lock disk for an MC/ServiceGuard cluster.
• Volume groups with any disks that have bad blocks in the bad block directory.
Unlike LVM, VxVM does not support bad block revectoring at the physical volume level. If there appear to
be any valid bad blocks in the bad block directory of any disk used in an LVM volumegroup, the group
cannot be converted. See Appendix A, “Conversion Error Messages,” on page 57 for actions to take in this
situation.
• Not enough disk space on the root file system to save a copy of each physical disk’s LVM metadata.
For large volume groups, for example, 200 GB using approximately twenty 9GB drives, the space needed
could be as much as 30 MB.
NOTE A workaround for this problem is to make /etc/vx/reconfig.d its own filesystem with more
free space.
• Volume groups with mirrored volumes.
A conversion fails if the LVM volume group being converted has mirrored volumes, but the system does
not have a valid license installed that enables mirroring for VxVM.
The analyze option in vxvmconvert, which is described in later sections, aids you in identifying which volume
groups can be converted.