Consider this:

 # fdisk -l /dev/sda Disk /dev/sda: 298.9 GB, 298999349248 bytes 255 heads, 63 sectors/track, 36351 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 36351 291884985 8e Linux LVM 

and this

 # df Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/VolGroup00-LogVol00 276883300 3610240 258981300 2% / /dev/sda1 101086 19371 76496 21% /boot tmpfs 1993292 0 1993292 0% /dev/shm 

(The OS is Centos 5.5 64-bit, the HW is IBM ServeRAID M1015 using an LSI MegaRAID BIOS)

Why does df use a long filesystem name instead of /dev/sda2?