Midrange Backup Strategies
Midrange backup technologies are more plentiful than ever. Here`s how large and small sites are using some of the leading alternatives.
By Ron Levine
Processing speed and memory used to be system bottlenecks, as those who remember the DOS 640K boundary and the agonizingly slow 8088 can attest. But today, with new limits being reached in memory usage and CPU speed, the bottleneck is often at the storage level--both primary (hard disks) and secondary (tape and optical) devices. From PCs to high-end servers, we`re being overwhelmed by our own data.
The data is coming from all quarters. Databases are growing, both the older transaction processing systems and the newer ones aimed at Internet and intranet users. Multimedia files can run into hundreds of megabytes. There are increasing demands for document imaging and, as networks grow, for backing up increasingly large user files.
Just as data files keep growing, so do operating systems and applications software packages. Where once a few floppy disks were sufficient to load an operating system or application, CD-ROMs are now required. Once this software is loaded, it becomes part of the storage problem.
At one time, the solution was obvious: bigger, faster hard drives. But hard drives are still relatively expensive, and many storage situations don`t require rapid access. For archiving and backup or for storing and retrieving seldom-used documents and files, slower but less expensive devices can meet users` price/performance requirements far better than more expensive counterparts.
Tape Still the Mainstay
The oldest backup media is tape, but this granddaddy of all storage media has been rejuvenated into a variety of forms that were undreamed of when 6,250-bpi 9-track tape was the standard. In fact, tape has evolved into a backup platform with some of the fastest transfer rates and largest storage capacities available.
Do you need to store 70GB or more of data, and only have a small window of time for backup? Digital Linear Tape (DLT) can handle it. The new DLT7000 drives can store 70GB in compressed mode (35GB in native mode) on a single cartridge, and the transfer rate is a blazing 10MBps compressed.
If you need more capacity, about a dozen manufacturers are now shipping DLT libraries. The latest entry comes from Qualstar, which this month began shipping the TLS-6000. This library houses up to four DLT4000 or DLT7000 drives and as many as 60 cartridges. Capacities range from 200GB to more than 4TB. Unlike conventional designs that use belts and pulleys, the Qualstar libraries are based on brushless DC motors and high- precision lead screws.
At the high end of the DLT library market, Breece Hill plans to ship within a few months its Saguaro system, which can theoretically scale up to 96 DLT drives and 1,680 cartridges, or 128TB in compressed mode, by linking up to eight libraries. Saguaro is expected to compete with high-end DLT libraries from vendors such as ATL Products and Storage Technology.
Tropicana Dole Beverages North America, the Bradenton, FLA-based international producer of orange juice and other beverages, uses DLT as a backup mechanism for its RAID subsystems. At Tropicana, an ATL Products 6/176 tape library, with DLT 4000 drives, provides up to 3.5TB (uncompressed) of data backup. When Tropicana upgrades to Quantum`s DLT7000 drives, the tape library could hold 7TB of storage.
Tropicana`s DLT library is directly connected to three host servers. Total storage for these servers is more than 230GB. Four additional servers are attached via various LAN links. Over 200 users worth of data is backed up to the library, and it stores all production, disaster recovery, and database restore files.
For many organizations, DLT is overkill from a price/performance standpoint. Many of these sites turn to tape devices with slightly slower transfer rates and smaller storage capacities. Examples include 8mm tape technologies from Exabyte and Sony.
Exabyte`s 8mm Mammoth format currently stores 40GB in compressed mode (20GB in native mode), while Sony`s Advanced Intelligent Tape (AIT) stores up to 50GB in compressed mode. The transfer rate is less than DLT`s, but still a very fast 6MBps in compressed mode. One downside to 8mm tape is incompatibility between the two 8mm formats.
Breece Hill plans to solve part of this compatibility quandary by delivering later this quarter an automated tape library, based on Sony`s AIT technology, that provides full backward compatibility with the installed base of Exabyte 8mm tapes. Breece`s FireFox libraries will be available in a number of configurations, supporting up to four drives for a maximum capacity of 3TB. The libraries accommodate mixed interchange of Sony and Exabyte 8mm tape in a single library enclosure.
At the lower end of the tape spectrum is DDS-3 Digital Audio Tape (DAT), a natural upgrade for LANs that previously used older DAT formats. Aimed at small and midsize networks, DDS-3 DAT can store 24GB of compressed data (12GB uncompressed) per cartridge with a transfer rate of 2.4MBps in compressed mode. DAT drive suppliers include Aiwa, Hewlett-Packard, Seagate, Sony, and Tecmar.
For smaller networks, Travan-class media stores up to 8GB of compressed data. Suppliers of Travan drives include vendors such as Aiwa, Exabyte, Hewlett-Packard, Seagate, and Tecmar.
Travan drives can be ideal for small businesses or work groups. For example, The Family Practice Ingrid Rule Clinic, in Loveland, CO, is a six-person outfit that relies on a six-station PC LAN to run their facility. The LAN includes one server and five PCs to maintain records on approximately 5,000 patients, to do electronic billing, and to handle typical back-office tasks. The system runs under Windows 95 and the Medisyst medical office software application package.
The clinic employs a Hewlett-Packard SureStore T4i Travan-class tape unit to provide server backup and disaster recovery protection. The 514-inch half-height SCSI-compatible tape device solved the clinic`s problem of not having a full- network file backup capability. When the system experienced a disk crash, they were back on-line within 20 minutes, thanks to the full 1.2GB daily and monthly backups performed by the staff. According to Walter Rayburn, a social worker at the facility, "Having all the data recovery files on one tape cartridge really made coming back up easy."
Optical Hangs On
At the low end of the optical disc market are CDs storing 650MB of data. At the high end are optical discs capable of storing more than 10GB of data per platter.
CDs were once limited to CD-ROMs. You could read them, but not write to them. With the advent of CD-R write-once technology, all that changed. Now users can write 650MB of data as easily as they write to floppies. The cost? A mere $6 per disc (about $450 per drive). CD-R technology provides inexpensive, durable file backups for smaller systems and networks, and the media can be read in any CD-ROM drive.
Just as CD-R technology moved CDs from a read-only to a write-once paradigm, CD-RW (rewritable) moves them to a write-many paradigm. Users can read, write, erase, and rewrite as often as needed on durable CDs, as freely as they once did on magnetic hard disks. The only downside to CD-RW is backward compatibility. All CD-RW drives can read CD-ROM and CD-R discs, but older CD-ROM readers can`t read CD-RW discs. For networks with many older CD-ROM readers installed on their PCs, CD-RW may be too costly a change.
Networked CDs are particularly attractive as reference library storage devices because of the media`s capacity and multiple-access capability. For example, GTE uses a CD tower on its Banyan Vines network for use by its accounting department to handle tax reference materials. "We didn`t want to put a CD-ROM drive at every desktop throughout the system. The tower solves the problem because all 78 users have access to the CDs, and multiple access to the same CD is also available," says Bob Cardoza, a GTE systems engineer.
The CDs store tax data that is accessed for research and to prepare tax forms. Meridian Data`s CD Net software connects the tower to GTE`s enterprise wide network. Currently, the tower houses seven drives; however, GTE plans to expand to 14 drives in the near future. Optionally, Meridian Data`s CD NetRecord software may be added to enable the addition of a CD- R drive.
At the higher end of the optical range is write-once, read-many (WORM) technology and rewritable optical discs. These disks come in different sizes (from 514-inch to 12-inch) and range in capacity from 2.6GB to 15GB per platter. Jukeboxes can provide terabytes of quickly accessible data.
IBM`s Kingston, NY, plant (the main manufacturing site for the company`s ES/9000 mainframes) found that optical storage was just what they needed. They`re using an RS/6000 and a Plasmon RF-1020JM optical disk jukebox to store and distribute over one terabyte of data and images. Connected to an FDDI network, and multiple Token Ring LANs with over 200 PS/2 workstations, the RS/6000 delivers interactive multimedia technical training and documentation from the central jukebox to technicians on the assembly line.
Plasmon also provided IBM with an optical disc jukebox interface and a disk management software program that transparently links the jukebox and the RS/6000, allowing users to access the jukebox using standard operating system commands. Application programs are executed exactly as they are on a hard drive, according to Woody Deetz, IBM`s manufacturing multimedia project planner.
"By using the RS/6000 as the processing front-end to the optical jukebox, it was possible to store one copy of all the image, audio, and full motion video files on a single storage unit and distribute it, when requested, to the PCs on the network," says Deetz.
DVD Comes On Strong
One of the newest and most exciting developments in storage technology is DVD. Offering crisper sound and clearer images than traditional CDs, DVD discs hold up to 4.7GB, or about 135 minutes, of video and are one of the best storage options for multimedia files.
International Data Corp., a market research firm in Framingham, MA, predicts that the market for DVD-ROM and DVD-recordable devices will exceed $10 billion, or more than 150 million units shipped, by the year 2001. IDC also predicts that almost 15% of all software will be available on DVD discs by the end of this year.
DVD-ROM is poised to make a run at the markets dominated by CD-ROM, but the DVD rewritable market may be marred by conflicting formats. In one corner is the DVD-RAM format supported by the DVD Forum, which includes such manufacturers as Hitachi, Matsushita, and Toshiba. In the other corner is DVD+RW. This technology is supported by Sony, Hewlett-Packard, Philips, Ricoh, Mitsubishi, and Yamaha--all of whom are active in the CD-RW market. Because the two formats are (at least initially) incompatible, some analysts have compared the impending battle to the VHS vs. Beta wars.
Ron Levine is a freelance writer in Carpenteria, CA. He can be reached at firstname.lastname@example.org.