What are Tape Drives and where are tape drives used ?

Earlier I spoke about Tape Libraries and its usage, today I’ll speak a bit about Tape drives and where they are use.

Tape drive is a data storage device which is used to read and write data that is stored on a magnetic tape. Tape drives are also known as ‘streamers’. Typically, Tape Drives are used for archival storage of data stored on hard drives.

The data capacities on these tape drives ranges from a few megabytes to several gigabytes. Their transfer speeds also vary considerably. Today you can find Fast tape drives in the market which can transfer as much as 20MB per second.

Tape drives come with sequential-access of data, which makes it slower to read/write data. ie..A tape drive spends significant amount of time winding tape between reels to read any piece of data on the drive. The advantage of hard disk drives over tape drives are that they allow random-access to data. ie..the read/write head moves to any random part of disk platters in a jiff. Thus rendering tape drives slow in the average seek time. however, regardless of slow seek time, they can stream data to tape very quickly.

The interfaces used to connect tape drives to a computer are SCSI, IDE, SATA, USB, FireWire to name a few. Tape drives assist autoloaders and tape libraries in loading, unloading and storing multiple tapes to increase their archiving capacity. So i guess its safe to say that tape drives have certain uses and are not outdated in some respects.

What is SCSI (Small Computer System Interface)?

SCSI is an acronym for Small Computer Systems Interface which basically attaches peripheral devices such as mouse, keyboard and printer to a computer, to transfer data simultaneously. These parallel interfaces are developed at Apple Computer and used in the Macintosh’s. SCSI ports are built into many personal computers and these are supported by all major operating systems.

The number of devices will depend on the bus width allowing up to 7 or 15 devices to be connected to single SCSI port.

Different SCSI are implemented and they are:

SCSI-1: Uses an 8-bit bus, and supports data rates of 4 MBps.

SCSI-2 (plain SCSI): Same as SCSI-1, but uses a 50-pin connector instead of a 25-pin connector, and supports multiple devices.

SCSI-3(Ultra Wide SCSI): Uses a 16-bit bus and supports data rates of 40 MBps.

Ultra2 SCSI: Uses an 8-bit bus and supports data rates of 40 MBps. It sends signals over two wires with data represented as the difference in voltage between the two wires. This allows support for longer cables.

Wide Ultra2 SCSI: Uses a 16-bit bus and supports data rates of 80 MBps.