Not dead yet
Tape storage makes a stand in archival and some backup applications
- By John Moore
- May 15, 2006
Tape storage lives on, despite expectations to the contrary.
Some observers have said the rise of disk storage — which offers faster backup and recovery speeds and a decreasing price tag — signals the end of tape. But Freeman Reports, a company that tracks the tape industry, forecasts a 6 percent revenue growth for compact tape through 2010. Compact tape covers a wide swath of the market, from tape drives for desktop computers to products that support low-end enterprise systems.
Government and industry executives assert that tape will continue to play a role in the evolving enterprise storage hierarchy. That role will increasingly involve archiving data as more backup chores go to disk.
One enduring attraction of tape cartridges is that administrators can remove them from drives and ship them to an off-site location. Not every organization will want to take on the cost and complexity of disk-to-disk remote mirroring, in which data simultaneously writes to a local and remote disk. For those organizations, tape represents a pivotal element of disaster recovery. Even some remote-mirroring adherents keep tape around as an additional failsafe.
Tape storage vendors, however, aren’t relying on the technology’s historical benefits to stay alive. They are boosting tape’s capacity and throughput to keep pace with the growing volume of data that most organizations are amassing.
In addition, vendors are increasingly pushing tape automation by introducing lower-cost autoloaders and improving the manageability of high-end tape libraries.
“I think tape is going to be around for a long time,” said Robert Rosen, president of Share, an IBM user group, and chief information officer at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).
Tape’s changing role
Kelly Fish, a storage specialist at reseller CDW, agreed that tape will press on, but in a different capacity.
“Its role is changing to more of an archival piece because of the falling prices of disk,” she said. “The archival piece is still very necessary. Putting in another level of backup is not something people are shying away from.”
Some users say disk cuts backup time nearly in half compared with tape. They also cite disk technology’s rapid data restore time. Think of the difference in finding a particular scene in a movie on a DVD vs. a VHS tape. The same mechanics apply to data storage.
Consequently, disk has begun to unseat tape from its traditional backup job. A growing number of information technology shops back up primary disk storage to near-line storage systems, which employ inexpensive disk technologies such as Advanced Technology Attachment (ATA) and Serial ATA.
Some ATA arrays act as virtual tape libraries, which interact with backup programs as if they were real tape libraries, meaning administrators don’t need to change routines.
But even organizations that use near-line storage often still add tape backup behind the two layers of disk storage. Industry analysts say more customers are pursuing the disk-to-disk-to-tape approach.
“Within the next five years, that will be the de facto way people are doing backups,” said Curtis Preston, vice president of data protection at GlassHouse Technologies, a consulting firm that specializes in storage. He said many IT departments already use this approach.
The Agriculture Department’s National Finance Center uses a mix of disk and tape to create a local backup of primary storage. A virtual tape server (VTS) handles most of the local data backup, but tape storage supplements the VTS, said Gilbert Hawk, the center’s chief information officer. Specifically, the center uses an IBM VTS product, which provides a disk cache as the front end of a tape library.
The National Finance Center also produces daily disaster recovery backups, using 1,500 to 2,500 tapes in the process. Those tapes go to an off-site location for storage. A yet-to-be-activated backup facility will provide disk-based remote mirroring of data.
Tape’s presence could diminish as the technology becomes a tertiary level of storage, Fish said. She added that some buyers may scale back the size of tape libraries and shift the storage budget to disk instead.
Consider this example of disk’s potential for consolidating tape libraries: IBM’s TotalStorage 3494 Virtual Tape Server Model B20 can house as many as 500,000 virtual tapes.
Tape becomes the medium of last resort in organizations that embrace disk-based backup and disaster recovery, said Tim Schilbach, network engineer at Apogen Technologies, a government solutions provider.
Only the destruction of primary and mirrored storage facilities or a problem with the link between them would send IT managers searching for tapes, he added.
In a disk-centric environment, “you don’t think about [tape] until something really, really bad happens,” Schilbach said.
But customers continue to think about tape and, in some cases, not just for archival purposes.
Richard Moore, director of production systems at the San Diego Supercomputer Center, said the organization does most of its backups directly to tape. The center operates six Sun Microsystems StorageTek PowderHorn tape silos, which it manages as a single library.
Moore said tape still maintains a cost advantage over disk despite declining disk prices. “For long-term storage, it continues to be a lower cost per byte,” he said, adding that tape’s price tag can beat the price of Serial ATA disk by a factor of 4 or 5.
“When you have the volumes that we do, that makes a big difference,” Moore added.
Similarly, Rosen said NIAMS uses tape primarily for backup, with three IBM tape libraries doing the job. He cited portability as tape’s big advantage. “You can pick it up and take it somewhere else,” he said.
In addition to backup, tape also continues to play a role in mainframe processing. “Certain jobs kick out code that needs to be written to tape,” Schilbach said.
Enterprise tape developments
Tape technology covers a spectrum from entry-level products for small offices and individuals to enterprise tape drives for mainframes. A vast midrange market lies in between. Formats vary from segment to segment.
Across the board, vendors aim to keep tape adherents in their respective camps by providing regular upgrades in capacity and performance.
At the mainframe-class level, which features tape drives that cost more than $30,000, IBM and Sun — via its acquisition of StorageTek — are the primary tape suppliers. The trend in this sector is toward bigger and faster drives. IBM and Sun introduced tape drives last fall that push capacity to 1 terabyte on a single cartridge.
IBM’s TS1120 tape drive uses 500G cartridges that the company said can offer as much as 1.5 terabytes of capacity with data compression. The mainframe environment may provide compression ratios of 3-to-1, according to IBM.
The tape drive offers a native, or uncompressed, data transfer rate as fast as 100 megabytes/sec.
In comparison, the TS1120’s predecessor model offers 300G of native capacity and a native data transfer rate of 40 megabytes/sec.
Sun’s T10000 enterprise tape drive, meanwhile, features native capacity of 500G uncompressed or 1 terabyte compressed on each cartridge. The product has a native data transfer rate of 120 megabytes/sec.
The San Diego Supercomputer Center is moving to the next-generation of high-end tape drives. The center has been using Sun T9940B tape drives with a native capacity of 200G, but it will upgrade to a tape drive with 500G of native capacity, said Moore, who declined to identify the vendor.
The tape drive upgrade will help propel the center’s tape storage capacity from 6 to 18 petabytes. The center stores 3 petabytes of data in its tape library. Moore said the center typically doubles its storage volume every 14 to 15 months. Much of the center’s archived data represents the output of computer simulations.
“We needed to upgrade to the next generation of tape drives because we would soon be hitting the limit of our capacity,” Moore said, adding that he expects the center’s new tape drives to be in production later this month.
The midrange tape market offers its own brand of innovation. Some market watchers refer to this segment as open systems, which — in tape industry terms — refers to server platforms other than mainframes. In this sector, so-called super drives mark vendors’ efforts to boost tape’s capacity.
Freeman Reports predicts that super drives, which the company defines as drives with a native capacity of 100G or more, will lead the way in the growth of the compact tape market. Super drives accounted for 63 percent of compact tape revenue in 2004 and will represent 79 percent of revenue in 2010, according to the market watcher. Freeman Reports has not yet released tape market data for 2005.
Sony, for example, offers super drives as part of its Advanced Intelligent Tape (AIT) product line. The company’s Super AIT drive provides 500G of native capacity and a native data transfer rate of 30 megabytes/sec. Sony’s AIT-3 and AIT-4 drives offer 100G or more of native capacity. The company’s AIT-5 drives, with 400G of native capacity, will probably debut in the fall, said Alan Sund, general manager for tape storage solutions at Sony Electronics’ Component and Business Solutions Division.
“The archival side is probably the growing side of the [tape] business, and part of that is driven by compliance issues,” Sund said.
Quantum, maker of the Digital Linear Tape (DLT) format, offers Super DLT products with 160G and 300G of native capacity. The company’s DLT-S4 drive, introduced in March, offers 800G of native capacity and 1.6 terabytes of capacity with compression, Quantum officials said.
Shane Jackson, Quantum’s director of enterprise product marketing, said products such as DLT-S4 fit the needs of customers who perform initial backups to disk and then migrate data to tape for longer-term archiving and disaster recovery. Capacity becomes the major consideration in such environments, he added.
Linear Tape-Open (LTO) provides another option in the midrange, open systems market, and industry analysts and consultants indicate that it is getting the most attention from customers. LTO drives garnered a 71 percent share of super drive shipments in 2004, according to Freeman Reports. Hewlett-Packard, IBM and Certance — now part of Quantum — developed LTO.
LTO 3, the latest LTO generation, provides as much as 400G of native capacity and a native data transfer rate of 80 megabytes/sec. LTO 4 will provide 800G of native capacity — 1.6 terabytes compressed — and a native data transfer speed of 120 megabytes/sec.
The LTO Program plans to release LTO 4 drive specifications later this year with the first products shipping soon after that.
Fish said she recommends LTO about 90 percent of the time.
“It’s quickly becoming the standard,” she said.
The development of LTO through a consortium, as opposed to a single company, and a long-term product road map boost customers’ confidence in the platform, Fish said.
“Its speed and capacity numbers continue to lead the marketplace,” she added.
The LTO Program has plans for at least two generations of the technology beyond LTO 4.
Vendors of other tape formats are hedging their bets by adding LTO to their product rosters. Quantum, for one, positions its DLT-S4 as a capacity play and emphasizes performance with its LTO solutions.
Overall, “performance and capacity are going up quite steeply in terms of tape drive technology,” Jackson said, adding that the increase is moving much faster in tape than disk.
Tape vendors aim to maintain that edge to remain viable.
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