Single connector attachment

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SCSI connectors, SCA top, standard 68-pin connector
SCSI backplane
SCA adapter for connecting SCA disks to standard (50 or 68 pin) SCSI cables

A single connector attachment (SCA) connects a hard drive directly to a backplane in the RAID housing or the drive bay . This avoids unnecessary plug connections, does not generate any taps (stubs) on the SCSI bus and makes settings on the hard disk (e.g. when replacing) superfluous, as the 80-pin SCA connector combines the power supply, setting jumpers and data lines . The SCSI ID of a device, which is set by jumper on the hard drive for normal SCSI hard drives, is determined by its position in the SCA backplane. Since SCA connectors are built in such a way that the ground contacts are always closed before the signal contacts (so-called "leading ground"), hotplugging (exchange during operation, without switching off) is possible.

SCSI hard disks with these connections are often used in servers or RAID systems (drive groups), whose downtime can be kept short by replacing a defective hard disk during operation.

With optional adapter boards, SCA disks can also be used in conventionally wired computers; however, hot plugging with such adapters is not recommended as exact mechanical guidance is not guaranteed.

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