device showing less total space than expected

Issue

• Hard drive is showing 931GB instead of 1TB.

# pvs /dev/sdz
  PV       VG   Fmt  Attr PSize   PFree  
  /dev/sdz      lvm2 a--  931.32g 931.32g

• fdisk shows the correct size

Disk /dev/sdz: 1000.0 GB, 1000001765376 bytes
255 heads, 63 sectors/track, 121576 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 65536 bytes
Disk identifier: 0x00000000