fsck is a tool to check the integrity and repair the file system if you have Paragon ExtFS software for Mac OS X the command to do these task is
Recently I had a problem that one hard drive was disconnected incorrectly and OS X can't mount the partition, to fix this issue I used this command:
sudo fsck_ufsd_ExtFS -y /dev/disk2s1
/dev/disk2s1 is the Ext partition, to be sure that it is the correct partition, we can use the command Diskutil to list the devices:
Is possible repair the partition using the graphical tool on
System Preferences > ExtFS for Mac OS X > Verify.