From MEPIS Documentation Wiki
Fsck is a program that checks the hard drives for file system consistency. In MEPIS 8, fsck runs after the OS has been booted 100 times.
You can change the time or stagger the drives to be checked by opening a terminal, becoming root and typing:
tune2fs -c <number of boots> /dev/sda<partition number>
So, for instance, to separate out the checks for three partitions, you would enter one at a time
tune2fs -c 98 /dev/sda1 tune2fs -c 99 /dev/sda2 tune2fs -c 100 /dev/sda3
This command stores these parameters in the nominated file system (partition), and is examined by the kernel at boot time hence there is no config file to check your settings however they can be viewed with the -l switch,
tune2fs -l /dev/sdb1 | grep -i mount
Using a pipe to grep outputs the mount info only
Last mounted on: <not available> Default mount options: (none) Last mount time: Wed Dec 28 10:22:20 2011 Mount count: 0 Maximum mount count: 92
You can also force a check if you feel the need by using MEPIS System Assistant.