Babineau said almost every major storage vendor now offers WORM disk as an option. Although he added that he does not track magnetic disk WORM pricing closely, he said they are typically priced similarly to ATA storage — “in the $2,000 to $5,000 per terabyte range.”
Greg Schulz, principal and analyst at StorageIO Group, said you should still expect to pay “a higher than entry-level” price compared to typical iSCSI or Fibre Channel (FC) drives. He pointed out that one of the benefits of new disk-based WORM is that some systems –again, he cited EMC Centera — support what is sometimes called content-based archiving, which means the WORM capability can be on any volume that you want, so that the array as a whole remains general purpose. “WORM capability is there if you want to use it but it isn’t all-or-nothing,” he said.
Is WORM tape dead?
Does all the new functionality available in disk mean that WORM tape is dead? No, said Schulz. “There is more data storage on tape now than at any time in history,” he noted. What is changing is that disk is helping to keep tape around longer because people are using disk more in a staging and caching role. Choosing to use WORM in either medium is a matter of understanding your requirements. “You need to determine what you need versus what you want,” said Schulz.
Hill at Mesabi advised WORM disk shoppers to select an array that can expand if necessary in the future. Some vendors also use the idea of virtual disks for providing WORM disk functionality. Hill said encryption is the key enabling technology for virtualizing WORM, “because it lets the data be located anywhere and, by having the key expire at a certain date, allows you to get rid of data when it is no longer required.” And, he added, virtualization tends to improve disk utilization.