Cleversafe also points out that dispersal codes don't, like common RAID, store data in some blocks and ECC information in others, but instead transforms all the data so each block contains encoded data and forward error correction information. It therefore requires a minimum set of blocks to be able to recover any data. Disk drives holding less than the minimum number of blocks are effectively encrypted and a "Black hat" couldn't scan the disk for social security numbers or other small but sensitive data items that could be on an orphaned drive from a RAID set.
Now, both NEC and Cleversafe are targeting their solutions at secondary storage applications where latency isn't a major concern. I wonder how erasure codes will work their way into more mainstream applications.