This message indicates that disk2 may be faulty; however, disk2 is probably an external disc.
What is the output of the following command?:
diskutil list; diskutil info /dev/disk2
Thanks for your Help
I think disk2 is an external usb drive for Time Machine
Last login: Tue Apr 19 19:25:30 on ttys000
aragorn:~ jeff$ diskutil list; diskutil info /dev/disk2
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_CoreStorage iMac 999.3 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
/dev/disk1 (internal, virtual):
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS iMac +999.0 GB disk1
Logical Volume on disk0s2
FD022CE3-784B-4E3B-9B5F-ADD1A932CD80
Unencrypted
/dev/disk2 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: Apple_partition_scheme *4.2 GB disk2
1: Apple_partition_map 30.7 KB disk2s1
2: Apple_Driver_ATAPI 2.0 KB disk2s2
3: Apple_HFS Applications Install... 4.2 GB disk2s3
/dev/disk3 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *3.0 TB disk3
1: EFI EFI 314.6 MB disk3s1
2: Apple_HFS Passport Backup 3.0 TB disk3s2
Device Identifier: disk2
Device Node: /dev/disk2
Whole: Yes
Part of Whole: disk2
Device / Media Name: Slimtype eBAU108 5 L
Volume Name: Not applicable (no file system)
Mounted: Not applicable (no file system)
File System: None
Content (IOContent): Apple_partition_scheme
OS Can Be Installed: No
Media Type:
Protocol: USB
SMART Status: Not Supported
Total Size: 4.2 GB (4193681408 Bytes) (exactly 8190784 512-Byte-Units)
Volume Free Space: Not applicable (no file system)
Device Block Size: 2048 Bytes
Read-Only Media: Yes
Read-Only Volume: Not applicable (no file system)
Device Location: External
Removable Media: Yes
Media Removal: Software-Activated
Virtual: No
OS 9 Drivers: No
Low Level Format: Not supported
Optical Drive Type: CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-R, DVD-R DL, DVD-RW, DVD-RAM, DVD+R, DVD+R DL, DVD+RW
Optical Media Type: DVD-ROM
Optical Media Erasable: No
aragorn:~ jeff$