Sim-Ex™ Practice Exams for Server+ : Practice Questions

SCSI Cable Length

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Q3.What is the maximum cable length typically allowed on a SCSI bus?

A. 1m

B. 12 to 24 m

C. 100m

D. 10k

Correct Answer: B


There are 3 main types of buses used. These are a) SATA, b) SCSI, and c) Fiber Channel
Bus type: SATA 
Cable length: 1 meter (3 feet) 
Speed : Fast
SATA I (revision 1.x) interface, formally known as SATA 1.5Gb/s 
SATA II (revision 2.x) interface, formally known as SATA 3Gb/s, 
SATA III (revision 3.x) interface, formally known as SATA 6Gb/s 

Bus type: SCSI (there are several types of SCSI buses)
Cable length: Typically 12 or 24 m
Speed : Fast (different speeds exist depending on SCSI type), but less than FC (costlier than SATA)

Bus type: Fiber Channel (FC)
Cable length: Up to 10Km (for single mode. Multi mode distances are less)
Speed (cost): Very fast and expensive too. Typical speeds are 1, 2, 4, 8, 16, 32, and 128 gigabit per second and primarily used to connect computer data storage to servers. 

The mayor reason for choosing/paying for SCSI/SAS over SATA, is not speed, but reliability. SCSI interfaces are meant for server grade operation (24X7) where as SATA interfaces are typically not as reliable as SCSI and primarily meant for PCs or off-line use

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