What you are referring to is basically HSM or Hierarchical Storage Management. It's on old idea that has gained a lot of interest lately, due to the recent advent of really inexpensive disks (especially the ATA variety).
There are a number of existing players in this space, including Veritas, the company that makes your Volume Manager. Since it's really still a niche market, giving you the "top" players is difficult, especially since many of them are written specifically for certain applications like Exchange. A directory of such products is available at here.
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This was first published in April 2003