SCSI Hard Drive

An SCSI hard drive is a type of storage drive that uses a much different system than what is likely found in your computer at home. The term SCSI actually means Small Computer System Interface. Most people pronounce the term as “Scuzzy” rather than saying the letters in the word. The main advantage to an SCSI hard drive is that it offers multiple drives that are chained to one single connection. This offers users the fastest data transfer speeds. It is designed for those computer systems and servers that are used constantly, around the clock.

The main difference between other systems such as ATA or SATA and SCSI hard drives is that an SCSI drive has a processor on the drive. This allows the drive to work independently from other computer specifications. While this does not offer huge advantages to home computer users, it does offer vital advantages to corporate users who may be running several computers at once and need the economic benefits of low-spec machines. More than one SCSI hard drive can be connected at once using a special adaptor that is connected to the motherboard of the host computer. Each one of these adaptors can operate up to fifteen different drives. Each of these drives will have a jumper switch that can be set from zero to fifteen and each drive connected to the host computer will be assigned a different number to help avoid conflicts. Those systems that need to run backup facilities constantly will benefit from this option.

SCSI hard drives are considered to be a bit more expensive than ATA or SATA hard drives of the same capacity. This is because the SCSI drives consist of more components that control the actual drive rather than those that provide storage. It is important to understand that SCSI hard drives can cost up to four times more than a typical SATA drive that contains twice as much capacity as the chosen SCSI drive. However, those who need the features that an SCSI hard drive offers find the cost to be more than bearable for the advantages that are gained.

SCSI hard drives are currently available in a wide variety of interfaces. The most common, and the first one released, is the parallel SCSI which is also known as an SPI. This variety uses a parallel electrical bus design. There are also other interfaces that do not solely rely on complete SCSI standards but still use the SCSI command protocol. SCSI interfaces are used on a variety of computers by different manufacturers such as Mac OS, Unix, Linus and Windows operating systems. They are used by plug-in adapters or implemented directly on the motherboards of various machines. However, with the inclusion of SATA and SAS hard drives, provisions for SCSI drive on motherboards may be completely discontinued, although there are a few manufacturers that do still market the SCSI interface for motherboards by supporting PCI-X and PCI-E.

It should also be noted that the SCSI bus can only be in one phase at a time. Not all controllers will use all of the phases. A well-written driver does not typically assume that these phases will occur. Instead, it should command the operation and then read the status to determine the phase that a specific device will need to do next. This technique will allow single drivers to work with many controllers. In the earliest uses of SCSI, writing single drivers to work with DTC and Xebec required that this approach be implemented while at the same time adding support for SCSI to the Ampro Little Board Z80.

This SCSI Hard Drive Review is Written/Updated on Jan 26th, 2011 and filed under Computer Hardware. Both comments and pings are currently closed.

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