HELP PLEASE. Working my brand new 5K Retina with latest Yosemite, and Lacie Rugged 1TB thunderbolt. It's been set up properly for a week, three partitions, 2 for backup (CCC and Time Machine) and a 3rd I call Lacie Windows which I use to put in data files. Out of nowhere I couldn't see my 3rd partition on my desktop and when I checked Disk Utility it says the partition is unmounted and will not remount. Repair doesn't work. It won't verify. I checked DiskUtil in Terminal and it shows as follows. Please help. It took me days to load my date into this partition and I don't want to lose it. Thanks.: Last login: Fri Dec 26 18:23:57 on console Roberts-iMac:~ Robert$ 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_CoreStorage 121.0 GB disk0s2 3: Apple_Boot Boot OS X 134.2 MB disk0s3 /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk1 1: EFI EFI 209.7 MB disk1s1 2: Apple_HFS Lacie CCC Backup 300.0 GB disk1s2 3: Apple_HFS Lacie TM Backup 375.0 GB disk1s3 4: Microsoft Basic Data 324.7 GB disk1s4 /dev/disk2 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk2 1: EFI EFI 209.7 MB disk2s1 2: Apple_CoreStorage 999.3 GB disk2s2 3: Apple_Boot Recovery HD 650.0 MB disk2s3 /dev/disk3 #: TYPE NAME SIZE IDENTIFIER 0: Apple_HFS Macintosh HD *1.1 TB disk3 Logical Volume on disk0s2, disk2s2 C00BC401-EA4B-495D-995D-35CAB0DCDFDA Unencrypted Fusion Drive Roberts-iMac:~ Robert$ ---------- AND, when I try repair disk, this is the message: ' Verify and Repair volume disk1s4Repairing file system.** /dev/rdisk1s4 Invalid sector size: 0 File system check exit code is 8.Updating boot support partitions for the volume as required.Error: Disk Utility cant repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files.