How fast is scsi

It also earned a reputation for being painfully expensive, as SCSI components were, and are, much more costly than their alternatives. Apple executives were criticized for using such expensive parts but responded by saying that the Macintosh was designed to be the best, and nothing else did the job better. If you need performance and have the money, SCSI is still the fastest out there.

SCSI is also one of the easiest technologies to implement. Install a host adapter, and plug the devices to the chain. The last device in the chain must be terminated. New devices are self-terminating. Earlier generations were single ended SE , meaning you had to plug in a terminator. If you want a device to boot, you use a jumper to specify it as ID 0 and go. SCSI has gone through seven distinct generations over the years as additional features were included to support new technology.

The number of variants and nicknames cause confusion. While the transfer rate may seem especially slow today, up to eight devices including the host adapter could be linked on a single chain. Those devices could fit a wide variety of needs, making it an excellent choice for the times. This format relied on a low-density pin internal connector and a low-density pin external connector.

To see a Centronics connector, take a look your printer cable. SCSI-1 had two ways to drive the electrical signal through the bus: single ended SE and differential. It allowed asynchronous commands with synchronous data transfers, another new feature.

The downside of all these new features was that it took until for SCSI-2 to be fully standardized. SCSI-2 used the low-density pin internal connector, low-density pin external connector non-Centronics , and a high-density pin connector.

CD-ROMs, scanners, tape drives, Zip drives, Jaz drives, and other external non-hard drive devices were, and still are, common. The fragmented and very slow process that created SCSI-2 inspired a fast and highly organized development for the next generation. The specific protocols allowed for improvements in various technologies without a total rewrite of the SCSI standard. For example, in this specification, hard drives are segmented into blocks and use the Block Command protocol while tape drives are linear devices that use the Stream Command protocol.

The significant difference in Fast Wide SCSI from previous versions was the addition of eight more data bits to the bus, now referred to as a bit bus. The bus speed, however, was the same as before. Average Access Time …….. The disk heads need to be in the right place to read the data, so the faster this happens the faster data is read.

Cache Size.. Means the size of the on board cache, It makes small differences in doubling the size but generally it is not very cost effective, but as ever, it is regarded that more is better. Internal Transfer Rate ……… This is generally the way that data is passed and read throughout the actual drive itself.

Usually this is higher than the actual transfer rate of the disk drive. So, there is a large variety of peripheral devices available for SCSI, including hard disk drives, floppy drives, CDs, optical storage devices, tape drives, printers and scanners to name a few. SCSI-1 Is the original standard which was developed back in , it features an 8-bit parallel bus with parity , it runs asynchronously at 3.

Although these improvements increased industry productivity, the limitations were that cable lengths were now reduced to 3 metres. Maximum cable length remained at 3 metres. By this standard was introduced. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams?

Learn more. Is SCSI "actually" better? Asked 11 years, 10 months ago. Active 9 years, 1 month ago. Viewed 33k times. Improve this question. Earlz Earlz 5 5 gold badges 12 12 silver badges 28 28 bronze badges. Add a comment.

Active Oldest Votes. Improve this answer. Greg Askew Greg Askew You will get a degraded array if the raid controller is waiting for a regular sata drive to recover, time out is too long on regular drives. This is true for controller cards like a 3ware card.

If you were using a ZFS raid system from solaris you can use regular off the shelf workstation sata drives. Dennis Williamson Zypher Zypher This all may be true For consumer drives.

Why isn't this the accepted answer? Beep beep Beep beep 1, 2 2 gold badges 18 18 silver badges 33 33 bronze badges. Javier Javier 8, 2 2 gold badges 22 22 silver badges 23 23 bronze badges.