I just purchased one of Lacie's 4TB Rugged thunderbolt external hard drives. It's being used as RAID 0 and I immediately reformatted it to one ExFat partition to make it compatible with both mac & windows. I'm on Yosemite 10.10.3 with a 2014 MBR 15.4''. Yesterday I transferred 1.6TB of data into it from another drive. Everything was fine until the next time I plugged it in to my macbook. The hard drive shows up on disk utility but the volume (OLDYELLOW) is greyed out and renamed as "disk2s2". I can verify and repair the hard drive and disk utility says everything is fine but I can't repair the volume. I get error messages "invalid sector size: 0" "File system check exit code is 8". Reformatting the hard drive is not an option. I tried DiskWarrior 5 but it will not allow me to rebuild the volume but says the hard drive is functioning properly. The only program that allows me to access the volume is Seagate File Recovery. I can see the volume with it's proper name (OLDYELLOW) and I can access every single file inside but I don't want to pay $100 unless it's my last option. I'm hoping someone has a fix for this issue because I need the video files inside the hard drive for a project. Thanks.