Quantum ProDrive 40S Product Manual page 91

Section 5 SCSI Programming Guidelines
MINIMUM PREFETCH (Byte 4) - Indicates to the ProDril'e the minimum number of logical
blocks to prefetch on a cache miss for a READ command. The valid range is 0 to 128; any value
outside this range will result in a CHECK CONDITION status with a sense key of ILLEGAL
REQUEST. The default value is one.
MAXIMUM PREFETCH (Byte 5) - Indicates to the ProDril'e the maximum number of
logical blocks to prefetch on a cache miss for a READ command. The valid range is 0 to 128; any
value outside this range will result in a CHECK CONDmON status with a sense key of ILLEGAL
REQUEST. The default is 16.
5.11. 1 0.7 Quantum UniQue Drive Control parameters. page Code 39J:l
Bit 7
I
6
5 I 4
3 1
I
1
I 0
Byte
0 RESERVED =0 PAGE CODE = 39H
1 PAGE LENGTH = 6H
2 DIO DII
fDB
j
RUEE
FDPE R::O
I
DUA
1
DRT
3 DDIS DELDIS RESERVED=O SSID SCSIADR
4-7
RESERVED=O
DIO • DISABLE IDENTIFY OUT (Byte 2, Bit 7) - Set to one indicates that the ProDrive
will
DQ!
require an IDENTIFY message from the initiator to
be
able to disconnect and reconnect. A
DIO bit set to zero indicates that the ProDrive will require the initiator to send the IDENTIFY
message to be able to disconnect. The default is zero.
DII • DISABLE IDENTIFY IN (Byte 2, Bit 6) - Set to one indicates that the ProDrive
will
D.Q!
send an IDENTIFY message after reconnecting to an initiator. A DII bit set to zero indicates
that the ProDril'e will send the IDENTIFY message after reconnecting. The default is zero.
FDB • FAST DEASSERTION OF BUSY (Byte 2, Bit
5) -
Not used nor required by
applications using the ProDril'e. It is included to maintain software compatibility with Quantum's
Q200 Series
TM
disk drives.
RUEE • REALLOCATE UNCORRECTABLE ERROR ENABLED (Byte 2, Bit 4)-
Set to one indicates that the ProDril't will automatically reallocate uncorrectable hard errors if the
ARRE bit in Page 1 of the Error Recovery Parameters is set. The uncorrectable (bad) data is written
to a new block and a new ECC (one that is correct for this
data)
is appended. Reading the new block
will result in a MEDIUM (re-allocated uncorrectable data read) error with Sense key set to 3, and sense
code set to AAH. Any write to the new block will clear this condition. A RUEE bit set to zero
indicates that the ProDril't will not attempt automatic reallocation if the hard error encountered is
determined to be uncorrectable. In this case, a CHECK CONDmON with a sense key of MEDIUM
ERROR - Uncorrectable Data Error will result. The default is zero.
FOPE - FILL DATA PATTERN ENABLED (Byte 2, Bit 3) - Set to one indicates that the
ProDril'e will write the data pattern specified in Byte 2 of the FORMAT UNIT command into every
user-accessible sector of the drive when a FORMAT UNIT command is executed. A FDPE bit set to
zero indicates that the ProDril't will ignore the information in Byte 2 of the FORMAT UNIT
command. Issuing a FORMAT UNIT command will typically cause loss of data, even if FDPE is set
to zero; users should back up data prior to formatting. The default is zero.
NOTE:
Bit 3 of byte 2 is reserved; it must
be
set to zero.
SCSI Programming Guidelines 5· 51