It's a known fact that BitTorrents can be abusive on hard drives, especially when running more than a few downloads. Things are constantly being written to the hard drive, file space being allocated, file contents verification and more. If you use Azureus for BitTorrent you can help out your hard drive by going to Preferences/Options » Files » Performance Options. Enabling disk caching is a must for Azureus users utilizing a 2.5" or smaller laptop-style hard drive, such as in a Mac Mini, which tends to get overworked rather easily.
By default, hard disk caching is enabled, but only to 4MB. You should boost this to somewhere around 16 to 24MB, depending on how powerful your system is. Azureus warns that anything over 32MB is probably overkill. Be sure to read the blurb to the right of the cache box as it will let you know what your maximum Java virtual machine size is, mine currently being 224MB. You want to keep your cache size at least 32MB below that number at all times or risk crashing Java.
Enter the cache size in MB you wish to use in the Size of cache in MB field, ensure that Enable disk cache is checked and click Save.