Seagate Ultra 160 ユーザーズマニュアル

Parallel SCSI Interface Product Manual, Rev. A                                        

   159

a. All SCSI devices are powered off during physical reconfiguration.

a. RST signal shall be asserted continuously by the initiator during removal or insertion.
b. The system shall be designed such that the SCSI device being inserted shall make its power ground 

and logic ground connections at least 1 ms prior to the connection of any device connector contact to the 
SCSI bus. The ground connections shall be maintained during and after the connection of the SCSI 
device to the SCSI bus.

c. The system shall be designed such that the SCSI device being removed shall maintain its power ground 

and logic ground prior to, during, and for at least 1 ms after the disconnection of any device connector 
contact from the SCSI bus.

The translation of the 1 ms time to mechanical provisions is vendor-specific.

a. All I/O processes for all SCSI devices shall be quiesced.
b. The system shall be designed such that the SCSI device being inserted shall make its power ground 

and logic ground connections at least 1 ms prior to the connection of any device connector contact to the 
SCSI bus. The ground connections shall be maintained during and after the connection of the SCSI 
device to the SCSI bus.

c. The system shall be designed such that the SCSI device being removed shall maintain its power ground 

and logic ground prior to, during, and for at least 1 ms after the disconnection of any device connector 
contact from the SCSI bus.

d. The SCSI device being removed or inserted shall employ transceivers that conform to the applicable 

requirements in ANSI SPI-5 specification, T10/1525D, sections 7.2.2 and 7.3.5.3, for glitch-free power-
ing on and off. The SCSI device shall maintain the high-impedance state at the device connector con-
tacts during a power cycle until the transceivers are enabled. Power cycling includes on-board 
TERMPWR cycling caused by plugging, and SCSI device power cycling caused by plugging and switch-
ing.

Any on board switchable terminators as well as SCSI device transceivers may affect the impedance 
state at the device connector contacts.

e. The SCSI device power may be simultaneously switched with the SCSI bus contacts if the power distri-

bution system is able to maintain adequate power stability to other SCSI devices during the transition 
and the grounding requirements in items (b) and (c) above are met.

f. The SCSI bus termination shall be external to the SCSI device being inserted or removed.
g. Resumption of I/O processes is vendor-specific but shall not occur sooner than 200 milliseconds after 

the completion of the insertion or removal event.

h. Bypassing capacitors connecting to the TERMPWR line on the SCSI device being inserted or removed 

shall not exceed 10 mF. For single-ended applications, SCSI bus terminations shall use voltage regula-
tion.

In a multimode environment any insertion or removal that changes the SCSI bus mode causes a trans-
ceiver mode change reset event (see Section 5.4.4).

a. All I/O processes for the SCSI device being inserted or removed shall be quiesced prior to removal.
b. A SCSI device being inserted shall make its power ground and logic ground connection at least 1 ms 

prior to the connection of any device connector contact to the SCSI bus. The ground connections shall 
be maintained during and after the connection of the SCSI device to the SCSI bus.