Physical partition limits

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In the design of Logical Volume Manager (LVM), each logical partition maps to one physical partition (PP). And, each physical partition maps to a number of disk sectors. The design of LVM limits the number of physical partitions that LVM can track per disk to 1016. In most cases, not all of the 1016 tracking partitions are used by a disk.

When this limit is exceeded, you might see a message similar to the following:

0516-1162 extendvg: Warning, The Physical Partition Size of PPsize requires the
creation of TotalPPs partitions for PVname.  The limitation for volume group
VGname is LIMIT physical partitions per physical volume.  Use chvg command
with -t option to attempt to change the maximum Physical Partitions per
Physical volume for this volume group.

Where:

PPsize: Is 1 MB to 1 GB in powers of 2.
Total PPs: Is the total number of physical partitions on this disk, given the PPsize.
PVname: Is the name of the physical volume, for example, hdisk3.
VGname: Is the name of the volume group.
LIMIT: Is 1016 or a multiple of 1016.

This limitation is enforced in the following instances:

When creating a volume group using the mkvg command, you specified a number of physical partitions on a disk in the volume group that exceeded 1016. To avoid this limitation, you can select from the physical partition size ranges of 1, 2, 4 (the default), 8, 16, 32, 64, 128, 256, 512 or 1024 MB and use the mkvg -s command to create the volume group. Alternatively, you can use a suitable factor that allows multiples of 1016 partitions per disk, and use the mkvg -t command to create the volume group.
When adding a disk to a pre-existing volume group with the extendvg command, the new disk caused the 1016 limitation violation. To resolve this situation, convert the existing volume group to hold multiples of 1016 partitions per disk using the chvg -t command. Alternatively, you can re-create the volume group with a larger partition size that allows the new disk, or you can create a standalone volume group consisting of a larger physical size for the new disk.

Partition limitations and the rootvg

If the installation code detects that the rootvg drive is larger than 4 GB, it changes the mkvg-s value until the entire disk capacity can be mapped to the available 1016 tracks. This installation change also implies that all other disks added to rootvg, regardless of size, are also defined at that physical partition size.

Partition limitations and RAID systems

For systems using a redundant array of identical disks (RAID), the /dev/hdiskX name used by LVM may consist of many non-4 GB disks. In this case, the 1016 requirement still exists. LVM is unaware of the size of the individual disks that really make up /dev/hdiskX. LVM bases the 1016 limitation on the recognized size of /dev/hdiskX, and not the real physical disks that make up /dev/hdiskX.