User Manual

SCSI Commands Reference Manual, Rev. J 406
www.seagate.com Parameters for direct access devices
BUFFER FULL RATIO field
The BUFFER FULL RATIO field indicates to the device server, during read operations, how full the buffer should be prior to requesting an inter-
connect tenancy. Device servers that do not implement the requested ratio should round down to the nearest implemented ratio as defined in
2.3. FCP devices attached to links that do not have the concept of interconnect tenancy shall round the ratio to zero and transmit data in a ven-
dor specific manner.
The value contained in the BUFFER FULL RATIO field is defined by 5.3.14.
BUFFER EMPTY RATIO field
The BUFFER EMPTY RATIO field indicates to the device server, during write operations, how empty the buffer should be prior to transmitting an
FCP_XFER_RDY IU that requests the initiator FCP_Port to send data. Device servers that do not implement the requested ratio should round
down to the nearest implemented ratio as defined in
2.3.
The value contained in the BUFFER EMPTY RATIO field is defined by 5.3.14.
BUS INACTIVITY LIMIT field
The BUS INACTIVITY LIMIT field indicates the maximum time that the target FCP_Port is permitted to maintain an interconnect tenancy with-
out data or information transfer, measured in transmission word increments. If the bus inactivity limit is exceeded or if the bus is inactive and
the target FCP_Port holding the bus detects that the limit is going to be exceeded, the device server shall end the interconnect tenancy. This
value may be rounded as defined in
2.3. A value of zero indicates that there is no bus inactivity limit.
Note. Because of the low overheads associated with initiating and closing bus tenancy on Fibre Channel links, device servers should end ten-
ancies immediately upon completing the required transfers.
The BUS INACTIVITY LIMIT field is not applicable for FCP devices attached to links that do not have the concept of interconnect tenancy.
DISCONNECT TIME LIMIT field
The DISCONNECT TIME LIMIT field indicates the minimum delay between interconnect tenancies measured in increments of 128 transmission
words. Target FCP_Ports in configurations having the concept of interconnect tenancy shall delay at least this time interval after each intercon-
nect tenancy before beginning arbitration. The device server may round this value to any value it prefers. A value of zero indicates that the dis-
connect time limit does not apply.
The DISCONNECT TIME LIMIT field is not applicable for FCP devices attached to links that do not have the concept of interconnect tenancy.
CONNECT TIME LIMIT field
The CONNECT TIME LIMIT field indicates the maximum duration of a single interconnect tenancy, measured in increments of 128 transmission
words. If the connect time limit is exceeded the device server shall conclude the interconnect tenancy, within the restrictions placed on it by
the applicable Fibre Channel configuration. The device server may round this value to any value it prefers. A value of zero indicates that there is
no connect time limit.
The CONNECT TIME LIMIT field is not applicable for FCP devices attached to links that do not have the concept of interconnect tenancy.
MAXIMUM BURST SIZE field
The MAXIMUM BURST SIZE field indicates the maximum size of all bytes in an FCP_DATA IU that the target FCP_Port shall transfer to the initia-
tor FCP_Port in a single Data-In FCP_DATA IU or request from the initiator FCP_Port in an FCP_XFER_RDY IU. This parameter does not affect
how much data is transferred in a single interconnect tenancy. This value is expressed in increments of 512 bytes (e.g., a value of 1 means 512
bytes, two means 1024 bytes, etc.). The device server may round this value down as defined in
2.3. A value of zero indicates there is no limit on
the amount of data transferred per data transfer operation. This value shall be implemented by all FCP devices. The initiator FCP_Port and tar-
get FCP_Port may use the value of this parameter to adjust internal maximum buffering requirements.