My Windows 7 bootcamp was running out of space. So I went to my mac OS and shrinked the size, rebooted the com and find that the Windows 7 partition was missing.
$ diskutil list /dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *121.3 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 49.7 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
4: Microsoft Basic Data 25.0 GB disk0s4
$ diskutil cs list
No CoreStorage logical volume groups found
MacBook Air, OS X Yosemite (10.10.2), null
