Backup Drives: Tape Drives and Archive HDDs

Tape drive, autoloader or backup hard drive

Three kinds of device turn up here. A tape drive writes LTO cartridges and is the usual choice for offline, long-term archives. An autoloader adds a magazine that swaps cartridges automatically, so a nightly job can span several tapes without anyone present. A plain backup hard drive suits disk-to-disk copies where files must be found quickly. Read the media format line, such as LTO-4 or LTO-8, because it decides which cartridges the drive accepts.

Capacity figures come in pairs, native and compressed, and so do speeds: the compressed rate assumes the data shrinks on the way to the tape. Plan around the native numbers unless your data compresses well. If the source cannot supply data fast enough, the drive repeatedly stops and rewinds a little, which slows the job and wears the tape, so a fast disk array or enough cache on the server matters as much as the drive.

Host adapters, cables and software support

Interface decides what the server needs. SAS drives, at 3 or 6 Gbit/s, need a SAS host adapter or controller and the right cable; Fibre Channel drives need a Fibre Channel adapter; IDE/ATAPI units belong to older machines with an IDE connector. A SATA port will not accept a SAS drive. Finally confirm your backup software lists the drive and its LTO generation, and that the operating system has a driver for it, especially with older units.

Questions about Backup Drives: Tape Drives and Archive HDDs

Do I need a SAS card for a tape drive?

If the drive has a SAS interface, yes: you need a SAS host adapter or controller in the server plus the right cable. Ordinary SATA ports will not connect to it. Fibre Channel and IDE drives each need their own matching adapter or port.

What is the difference between native and compressed transfer rate?

Native is the speed at which the drive writes raw data. The compressed rate assumes the data shrinks first, so more of it arrives per second. Real throughput depends on how compressible your files are and how fast the source can supply them.

Is a backup hard drive different from an ordinary one?

Often only in labelling. What matters is the interface, rotation speed, size and whether your controller supports it, so compare those details rather than the word backup. Enterprise SAS models suit sustained, continuous workloads.