A few other Disk Based Storage Vendors
In addition to Copan, I found a few other vendors in this space. I have not looked at them but the market seems to have a fair amount of competition:

• Data Domain (they seem to be the largest in the space and recently did an IPO)
  
• Sepaton Inc
• ExaGrid
• Diligent Technologies

Looking at the onerous eDiscovery requirements, disk-based backup and archive solutions are clearly the way to go.