Here are three reasons to use external USB hard drives for backup --- and three reasons not to.
They're easy to use. Many programs offer one-click backup to USB drives. Installation is also simple: Plug the drive into the USB cable, plug in the power supply (if needed) and let Windows recognize the drive. USB has elaborate software and hardware features to make connecting any USB device just about as foolproof as possible. In addition, most backup software now supports USB devices.
They're cheap. The drives themselves are inexpensive, with street prices for external 250 GB USB drives touching $100 and 500 GB drives available for less than $300. This is less than most entry-level tape drives and there is no additional media cost.
They're flexible. External USB drives are highly portable and can be used to back up several computers on the same drive.
However, there are also valid reasons not to back up to USB hard drives.
They're not a complete backup solution. USB disk backup is best suited to an intermediate level of backup –- somewhere between things like System Restore on Windows XP for quick file recovery and archival storage. With the proper software, USB drives are suited for file recovery. With imaging software, such as Acronis True Image or Norton Ghost, they are very
They have fixed capacities. Unlike tape or DVD, where a backup can span several tapes or disks, the capacity of a conventional external hard drive is limited. The current maximum capacities of USB external drives – about 500 GB – do not leave a lot of space for even a medium-sized server, especially when you are doing a complete cycle of incremental and full backups. The fixed capacity also means you're putting all your backup eggs in one basket. All your backups, no matter how redundant or how often you do them, are going onto one drive. If it fails, you're in trouble.
They're not cheap. The fixed capacity of external USB drives influences the economics of using them for backup. USB is only cheap if you can fit all the data you need to back up onto a single hard drive. What's more, if you can't (or don't want to) handle archival backup with a built-in CD or DVD drive, you'll have to purchase additional hardware, such as a tape drive.
Bottom line: USB hard drives are best suited for backing up fairly small amounts of data on systems with limited connectivity, such as laptops, desktops and small servers, where archival backup can be handled by the system's built-in DVD or CD drive. For larger amounts of data or more sophisticated requirements, better to use a tape drive or other system.
About the author: Rick Cook specializes in writing about issues related to storage and storage management.
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- Topics: Backup
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This was first published in September 2006