Fujitsu M2488, Руководство по эксплуатации продукта

Страница: 188 / 528

TAPE UNIT SCSI COMMANDS M2488 PRODUCT GUIDE
4-106 CG00000-011503 REV. A April 1997
4-3.24.2 REPORT DENSITY SUPPORT Data
The REPORT DENSITY SUPPORT data contains a four-byte header, followed by one or two
DENSITY SUPPORT data blocks. The DENSITY SUPPORT data blocks are in numerical
ascending order of the primary density code value in each block. Each DENSITY SUPPORT data
block represents a particular format including physical density information. The information in the
DENSITY SUPPORT data blocks is intended to provide the initiator with a detailed description of
the recording technologies supported by the logical unit. Density code values returned in the DEN-
SITY SUPPORT data blocks may be used by the initiator in the Block Descriptor of a MODE
SELECT command, however, the M2488 always operates in a fixed density support mode (i.e 18-
track read; 36-track read/write) independent of the value sent in the Block Descriptor (reference
the MODE SELECT command specification in section 4-3.12 on page 4-51).
Table 4-100. REPORT DENSITY SUPPORT Field Description
BYTE BIT VALUE DESCRIPTION
0 0-7 44h Operation code.
1 0
0b
1b
The Media bit indicates which DENSITY SUPPORT data blocks are to be
returned.
DENSITY SUPPORT data blocks are to be returned to the initiator for
densities supported by the logical unit for any supported media. This
includes density 09h described in Table 4-102 on page 7-107 and density
28h described in Table 4-103 on page 7-108.
Density support data block(s) is to be returned to the initiator for densities
supported by the mounted medium:
a) If the mounted medium is a standard-length tape, there are two DEN-
SITY SUPPORT data blocks returned. This includes density 09h described
in Table 4-102 on page 7-107 and density 28h described in Table 4-103 on
page 7-108.
b) If the mounted medium is an extended-length tape, there is one DEN-
SITY SUPPORT data block returned: density 28h described in Table 4-
103 on page 7-108.
Notes:
a) The DENSITY SUPPORT data block’s Capacity field corresponding to
density 28h is dependent on the tape length when the Media bit in the CDB
is set. Reference the description of the DENSITY SUPPORT data block’s
Capacity field in Table 4-104 on page 7-109.
b) If the Media bit is one and the logical unit is NOT READY, CHECK
CONDITION status is generated with a sense key of NOT READY.
7-8 xxh Allocation Length field specifies the maximum number of bytes that the
initiator has allocated for returned REPORT DENSITY SUPPORT data.
An allocation length of zero indicates no data is to be transferred. This
condition is not considered an error.
The target terminates the DATA IN phase when allocation length bytes are
transferred or when all available data is transferred to the initiator, which-
ever is less. An allocation length of at least 6Ah (106) should be specified
in order for all of the maximum possible bytes to be returned to the initia-
tor.