Adaptec 2074700-R User Guide - Page 167

Domain Validation

Page 167 highlights

ICP RAID Navigator Synchronous Transfer and Synchronous Transfer Rate Different from the older asynchronous transfer mode, synchronous transfer offers higher transfer rates on the SCSI bus. The maximum synchronous data transfer rate depends on the width of the SCSI bus (8 bit narrow SCSI, 16 bit wide SCSI) and the frequency of the signals on the SCSI bus (10 MHz for Fast SCSI, 20 MHz for Ultra SCSI and 40 MHz for Ultra2 SCSI and Ultra160/320 SCSI). The maximum data transfer rates are shown in Table 11-17. Table 11-17. Data Transfer Rates Fast SCSI Ultra SCSI Ultra2 SCSI Ultra160 Ultra320 † (LVD SCSI (low voltage differential) only) Narrow SCSI (8Bit) 10 MB/s 20 MB/s - Wide SCSI (16Bit) 20 MB/s 40 MB/s 80 MB/s † 160 MB/s † 320 MB/s † Note: The maximum synchronous data transfer rate between a SCSI device and the ICP RAID controller can be limited. This limitation may become necessary if a particular SCSI cabling does not allow the maximum rate the controller and the drive could achieve. Adjust the synchronous transfer rate in the SCSI parameters / Initialize menu. Note: To select a transfer rate above 10 MB/s the protocol must be set to SCSI-III. Higher frequencies (single ended SCSI) require better cabling, shorter cables and a professional termination of the SCSI bus. Domain Validation Domain Validation is a cyclical check of the correct data transfer at a given rate for ICP RAID controllers with Ultra160 SCSI channels. Normally this parameter is Off. Disconnect This SCSI feature enables a SCSI device to disconnect from the SCSI bus. By releasing the SCSI bus while the device doesn't need it, the bus becomes free for other devices to transfer or receive data. An example of a disconnect situation is a hard disk that needs time to read data from its media after receiving a read command. It may then disconnect from the SCSI bus so that other devices can transfer data. Later on it reconnects when it is able to deliver the data instantly. You can change the disconnect setting for a hard disk in the SCSI parameters / Initialize menu. Software Installation and User's Guide 167

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Software Installation and User’s Guide
167
ICP RAID Navigator
Synchronous Transfer and Synchronous Transfer Rate
Different from the older asynchronous transfer mode, synchronous transfer offers higher
transfer rates on the SCSI bus. The maximum synchronous data transfer rate depends on
the width of the SCSI bus (8 bit narrow SCSI, 16 bit wide SCSI) and the frequency of the
signals on the SCSI bus (10 MHz for Fast SCSI, 20 MHz for Ultra SCSI and 40 MHz for
Ultra2 SCSI and Ultra160/320 SCSI). The maximum data transfer rates are shown in
Table 11-17
.
Note:
The maximum synchronous data transfer rate between a SCSI device and the ICP RAID
controller can be limited. This limitation may become necessary if a particular SCSI
cabling does not allow the maximum rate the controller and the drive could achieve.
Adjust the synchronous transfer rate in the SCSI parameters / Initialize menu.
Note:
To select a transfer rate above 10 MB/s the protocol must be set to SCSI-III. Higher
frequencies (single ended SCSI) require better cabling, shorter cables and a professional
termination of the SCSI bus.
Domain Validation
Domain Validation
is a cyclical check of the correct data transfer at a
given rate for ICP RAID controllers with Ultra160 SCSI channels.
Normally this parameter is Off.
Disconnect
This SCSI feature enables a SCSI device to disconnect from the SCSI bus. By releasing
the SCSI bus while the device doesn’t need it, the bus becomes free for other devices to
transfer or receive data. An example of a disconnect situation is a hard disk that needs
time to read data from its media after receiving a read command. It may then disconnect
from the SCSI bus so that other devices can transfer data. Later on it reconnects when it is
able to deliver the data instantly. You can change the disconnect setting for a hard disk in
the SCSI parameters / Initialize menu.
Table 11-17. Data Transfer Rates
Narrow SCSI
(8Bit)
Wide SCSI
(16Bit)
Fast SCSI
10 MB/s
20 MB/s
Ultra SCSI
20 MB/s
40 MB/s
Ultra2 SCSI
-
80 MB/s
Ultra160
-
160 MB/s
Ultra320
-
320 MB/s
(LVD SCSI (low voltage differential) only)