HP-UX 11i v3 Using LVM Logical Volume Snapshots (September 2010)

• Current pre-allocated PE

Displays the total number of extents currently pre-allocated to all space-efficient snapshot logical

volumes in the volume group. When extents are picked from the pre-allocated pool of a particular

snapshot to cater to data unsharing or when a space-efficient snapshot is deleted, this value is

decremented. When you use lvextend to increase the pre-allocated pool size of a snapshot

logical volume, this value is incremented.

• Cur Snapshot Capacity

Displays the total capacity of all the snapshots configured in the volume group. Regardless of the

type of snapshot, the capacity of the snapshot is equal to that of original logical volume.

• Max Snapshot Capacity

Displays the maximum snapshot capacity that is allowed in a volume group. This value is equal to

the VG Max Size specified during volume group creation.

In the vgdisplay verbose output, the following new fields are added for snapshot logical volumes:

• Snapshot Status

Indicates the snapshot as operative, inoperative, or over-commit.

• Pre-allocated LE

Displays the total number of extents that have been pre-allocated for a space-efficient snapshot. This

value is incremented when the number of extents in the pre-allocated pool is increased using

lvextend. This field is not displayed for a fully-allocated snapshot.

• Current pre-allocated LE

Displays the number of logical extents currently present in the pre-allocated extents pool. This value

excludes those extents that have already been picked for unsharing. This field is not displayed for a

fully-allocated snapshot.

• Current pre-allocated PE

Displays the number of physical extents corresponding to Current pre-allocated LE and

the number of mirror copies of the space-efficient snapshot. This field is not displayed for a

fully-allocated snapshot.

• Unshared LE

Displays the number of extents of the snapshot logical volume that have been unshared.

In the vgdisplay verbose output, the following new field is added for physical volumes:

• Current pre-allocated PE

Displays the total number of physical extents of the physical volume that are present in the

pre-allocated pool of all the snapshot logical volumes of the volume group. This value represents

those extents that have not yet been picked for unshare.

The following is the vgdisplay output of a Version 2.2 volume group vg01, which has two

snapshot logical volumes. The unshare unit of the volume group is 2 MB and the maximum volume

group capacity is 128 t. Both snapshots are created off an original logical volume of 1 GB size,

therefore the current snapshot capacity in the volume group is shown as 2 GB. The Current

pre-allocated PE shows the total pre-allocated extents of all the snapshot logical volumes in the

volume group.