Tape-Based Storage: Its Cheap, Its Fast, It Holds A Lot Of Data
Traditionally the lowest-cost medium for data storage, tape has taken a back seat in recent years to more costly optical media (CD-R, CD-RW, DVD-R) that can be more quickly accessed for information and are said to have a longer shelf life.
New advances in tape technology, however, are changing the way information technology (IT) departments think about storing their companies critical data on tape.
According to Rich Gadomski, director of marketing for Maxell Corporation of America, a tape manufacturer based in Fair Lawn, N.J., tape is still the cheapest medium in terms of cost per megabyte, and transfer rates of tape systemslong held to be one of their disadvantages”have improved dramatically.
“Storage has become a buzzword because of the Internet, e-mail and e-commerce,” says Gadomski. “Its a pretty hot commodity right now.”
When it comes to tape, Gadomski notes, DLT (digital linear tape), and “particularly DLT-IV” are the mainstay for storage in larger network and mainframe environments. DLT-IV tape cartridges hold up to 40 gigabytes (GB) of data, and up to 80GB if data compression software is used. This format has been around for about six years, starting out with cartridges that held 10GB (20GB compressed).
According to Gadomski, tape is the “ideal” storage medium for mainframe systems, storage area networks (SANs) and other network servers. “Its removable, which makes it good for archiving or disaster recovery,” he explains. “You can take it to a remote site [for storage], as opposed to a fixed hard disk.”
Just recently, SDLT-I (super-DLT) format tapes became available, offering users up to 110GB native and 220GB compressed, says Gadomski. (By comparison, read-only DVDs can store up to 17GB, while rewritable DVDs hold up to 9.4GB.) The SDLT-I cartridges are currently available from some drive manufacturers and will be shipped by Maxell this month or in July, he adds.
While shelf life seems to be one of the main issues with regard to long-term storage of data on tape, Gadomski maintains that “all of our newer tape products are rated at 30 years life span, under normal use conditions and not subjected to abuse.” (Industry estimates for the life span of optical media range from 100 to 200 years.)
“Technically speaking,” says Gadomski, “if you want to retain documents for legal reasons, its better stored on write-once products such as CD-R. DVD-R will also be applicable for long-term storage.” Gadomski explains that for information that would be admissible in courts, media that cant be “written to” (re-recorded) are preferable. “Tape is ideal for backup and disaster recovery,” he notes.
Gadomski adds that data transfer rates (the speed at which data is transferred between media and computer) are now more than 10MB per second for tape, compared to previous speeds of 2 to 3MB. “Its more than tripled over the last five years,” he adds. “It still doesnt approach hard disk speed, but it does reduce the backup time required.” (Transfer rates for hard disks are 22MB per second, says Gadomski.)
“No one is saying that [tape] is inexpensive but slow. The drives have gotten faster, relatively speaking,” Gadomski asserts.
Yet another “hot” tape standard is LTO (linear tape open), a standard developed two years ago by drive manufacturers Hewlett-Packard, IBM and Seagate, says Gadomski. LTO tape cartridges, which began shipping last fall, hold 100GB native and 200GB compressed, putting them in competition with SDLT. “IBM and H-P will also support SDLT-I, however,” Gadomski adds. “Both have widespread industry support.”
More importantly, says Gadomski, both standards “have migration paths that can [ultimately] take them up to 500GB native capacity. The technological capabilities exist.”
When it comes to the cost of these systems, LTO and SDLT tape drives sell for about $6,000, while “library” systems for larger operations may range into the hundreds of thousands of dollars, says Gadomski. DLT systems sell for between $1,500 and $5,000, he adds.
Looking to the future of tape storage, Gadomski points to the new Sony tapes that feature “a chip on the cartridge.”
These new tapes, called AIT (advanced intelligent tape) feature high data transfer rates achieved through “Memory in Cassette (MIC)” technology, according to the AIT Technology Forum on its Web site.
The AIT Technology Forum is a group of manufacturers who have committed to the standard, including ADIC, Compaq, Cybernetics, Matsushita Media Group and Sony Electronics Recording Media and Tape Streamer Groups.
Using MIC, “its no longer necessary to read through an entire tape to find a filea process that could take hours,” says the AIT site. “The MIC chip knows where your file is and takes you right to it. MIC is a 64KB flash memory chip that is incorporated into the data cartridge. The MIC chip contains a tape log, search map and other user-definable information.” Drives using MIC can locate selected data in less than 20 seconds, the site adds.
Other advantages of AIT include a low “tension factor” (tension on the tape creates wear and tear on both the media and the read head) and a “highly smooth, pure and protective diamond-like carbon coating, which reduces drive head wear and head contamination, and increases the number of passes the media can withstand without degradation,” says the AIT Forum.
Reproduced from National Underwriter Edition, June 22, 2001. Copyright 2001 by The National Underwriter Company in the serial publication. All rights reserved.Copyright in this article as an independent work may be held by the author.