With disk backup, end users can run familiar tools such as Microsoft Explorer and backup software designed for ease of use. Also, external disks are simpler to handle than bulky portable tape drives with their associated fragile media. With the use of speedy USB 2.0 and Apple Computer FireWire peripheral interfaces, connectivity is a snap, too.
But when you're talking corporate servers or other bigger systems, deciding which way to back up isn't so clear-cut. Businesses need off-site storage, even if it means Joe in IT has to take home the tapes. Disk-based backup can work well, for instance, in remote locations where there's no on-site IT support. A backup often fails when the non-IT person tasked with tape-change duties doesn't do the job. Off-site locations can also have less than perfect conditions, like dirty tape drives, that can cause unnecessary backup problems. That's where a D2D system makes more sense.
Still, disk-based near-line backup has its problems, too. You can inadvertently replicate an error or virus on your only backup when you deploy the point-in-time or incremental snapshot features of a D2D device. And the ever-changing nature of the snapshot can leave you without a viable backup. To prevent these problems, back up to a tape device once a day as well, or keep a separate, once-a-day snapshot of the data for up to a year (depending on your company's data retention policy).
ATA (Advanced Technology Attachment) technology has finally shaken its bad reputation as an unreliable interface for storage devices. While SCSI and Fibre Channel drives are built with longevity and reliability in mind, that wasn't always the case for ATA. But the quality of ATA devices has much improved, and ATA and its immediate successor, Serial ATA, are now giving SCSI and Fibre Channel drives a run for their money. Although ATA is still slower than SCSI and Fibre Channel--anywhere from 50 Mbps to 150 Mbps--it's becoming more popular as an inexpensive backup and recovery option.
The speed gap, however, has gradually been narrowing over the past several years. Low-end drives have become faster and their capacity has increased. These low-cost ATA drives with huge capacity led to the development of today's D2D (disk-to-disk) near-line backup devices and an explosion in the NAS (network-attached storage) market. D2D vendors are including interfaces on their arrays to handle direct Fibre Channel connections to the SAN or SCSI connections, so ATA has finally found its way into the data center.
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