Offsite Storage

By Henry Baltazar  |  Posted 2002-01-14 Print this article Print

Offsite Storage

Every company, regardless of size, should have a removable media backup system with offsite storage for media. By setting up an offsite storage repository, IT managers can ensure that they will be able to recover most data in the event of a geographic-level disaster (such as fire or flood), where all co-located servers and storage facilities are rendered unusable.

It is important to note, however, that there will be a gap in data—possibly crippling—if backups are the only form of data protection employed. Backups are really nothing more than snapshots of data taken at scheduled intervals; data created or modifications made between the time of the last backup and the disaster is lost forever unless it can be reconstructed from transaction or other activity records that might be maintained by other parties.

For most companies, magnetic tape is still the removable storage medium of choice.

Magnetic tape has a long shelf life—usually a couple of decades—which makes it a good medium for archiving data. And newer tape formats, such as SuperDLT (digital linear tape) and LTO (Linear Tape Open), have larger capacities than previous generations—allowing storage of more than 100GB of data on a single tape.

Tapes data transfer rates are relatively slow, with the fastest midrange drives transferring data at about 11MB to 30MB per second. Depending on the size of the data set, a full data restore from tape can take anywhere from a few minutes for a small server to a couple of days for large data centers.

The three main technologies to watch in the enterprise-class range are Quantums Corp.s SuperDLT, the new LTO standard (from a vendor consortium composed of heavyweights such as IBM and Seagate Technology LLC) and Storage Technology Corp. (StorageTek), with its T9840B Fibre Channel tape drive.

High-end magnetic tape drives such as the T9840B can manage data transfer rates of roughly 19MB to 70MB per second, depending on the compressibility of the data being backed up: Traditional business records tend to be highly compressible, but multimedia files with their own compression schemes leave little room for additional compaction. However, these drives have somewhat limited capacity (20GB native and 40GB compressed capacity per tape).

In the workgroup/midrange market, there is a wide range of tape products, including Sony Electronics Inc.s AIT tape drive and offerings from smaller vendors such as Ecrix, OnStream Data B.V. and Benchmark Storage Innovations Inc. These products are less expensive than enterprise-class offerings but by design are slower and have smaller capacities.

Magnetic tape drives are expected to hit capacities of 1 terabyte and speeds of 100MB per second in 2007, according to projections listed on Quantums SuperDLTs road map (see Web resources list, next page).

However, with the capacity of IDE hard drives doubling every year or so, IT managers will soon have another cost-effective alternative to magnetic tape as a backup medium. Because IDE hard drives can provide direct data (unlike tape solutions, which must be restored to a hard drive before users can readily access data), IDE hard drive solutions will be able to provide data on demand, even when primary storage solutions go down.

Although tape has a longer life span, hard drives can be protected with RAID to ensure hardware fault tolerance.

Network Appliance Inc.s forthcoming NearStore line combines storage management software with an inexpensive IDE drive to provide consolidated backups and rapid data recovery. NearStore will begin shipping in the first half of this year, with the ability to scale from 12 terabytes to 100 terabytes at a cost of roughly 2 cents per megabyte.

The software you invest in will also have a significant impact on the success of your backup solution. A key thing to look for is a system that will allow the management and backup of multiple platforms from a single console, which will significantly reduce management overhead. Good options include those from Veritas Software Corp., Legato Systems Inc. and Bakbone Software Inc.

eWeek Corporate Partner Robert Rosen, CIO of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, uses Computer Associates Inc.s ArcServe and scripts for backups, but he said the NIAMS long-term plan is to set up a consolidated backup system.

Another feature to look for when evaluating backup software is snapshot backups, a technology that allows the backup of data while an application is still running. Usually associated with database backups, snapshot backups are a necessity for companies that have applications that must run 24-by-7 and are especially effective for protecting e-mail servers. Backup snapshot capabilities are available as an add-on to Veritas NetBackup system, for example.

Fibre Channel-based backup systems, which off- load backup traffic from IP networks and onto Fibre Channel SANs (storage area networks), have grown in popularity during the last few years. In addition to off-loading the IP network, Fibre Channel SAN backups—when properly designed—allow the sharing of expensive resources such as tape libraries and Fibre Channel networking equipment. Before investing (switches can cost from $10,000 to $100,000, depending on the number of ports, and host bus adapters cost around $1,000 per server) make sure that your backup system can support all of the platforms in your network.

eWeek Corporate Partner Gary Bronson said the move to Fibre Channel will allow his organization to consolidate all backups. "With the recent implementation of our Compaq SAN, we are planning to implement centralized backup for all systems in our data center, including Windows NT and Solaris systems," said Bronson, enterprise operations manager, information technology, at construction and engineering firm Washington Group International Inc., in Boise, Idaho. "We focused on backing up the Solaris systems first and NT within the next month."

One of the main benefits of Fibre Channel is its ability to support network links several kilometers long. This allows backup sites to be set up far from the data center, which provides fault tolerance in the event that the servers and storage units in the data center are damaged.


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