I have a hard drive that I use for storing and working with large tar archives, ranging from less than one MB to hundreds of MB and I have thousands of these archives. It is not convenient to format this drive and start over often, which I do about once every 6 months due to the problem I have. It seems that after a few months of working with these archives, unpacking, making modifications and tarring them back up, the whole system will get very slow, but particularly this drive. Since I cannot find any defrag programs, I'm not really sure what to do other than completely wipe the drive and restore the archives.