VTL的核心实现

    今天终于搞清了Tape的核心指令集了，仔细数数，也就那么多，所以根据iSCSI Target Disk去实现Tape的话应该很容易。可惜SSC中的指令集，Wireshark不识别呀。

 

The commands that the tape devices need to support tape drive self-identification are listed in the following table.

Table 1: Commands Needed to Support Tape Drive Self-Identification

 

Command	Page Code	Type (Mandatory/Optional)	Specified in...
INQUIRY (12h)	0	Mandatory	spc4r06, page 155
INQUIRY (12h)	0xB0	Optional	ssc3r03, page 147 Sequential-access device capabilities VPD page
MODE SENSE (15h)	0x10	Mandatory	spc4r06, page 324 ssc3r03c, page 132
MODE SENSE (15h)	0x0F	Mandatory	ssc3r03c, page 128
READ BLOCK LIMITS (05h)	N/A	Mandatory	ssc3r03c, page 93
REPORT DENSITY SUPPORT (44h)	N/A	Mandatory	ssc3r03c, page 102
REPORT SUPPORTED OPERATION CODES (A3h)	N/A	Optional	spc4r06, page 229 spc4r06, page 234

 

INQUIRY
Standard inquiry data should include T10 VENDOR IDENTIFICATION and PRODUCT IDENTIFICATION. Page 0xB0 should include the WORM bit to report if the tape device supports WORM mode operation.

MODE SENSE
In the mode parameter header, MEDIUM TYPE should be reported. And in the Block descriptor, DENSITY CODE and NUMBER OF BLOCKS should be reported. If the tape devices support variable block size, NUMBER OF BLOCKS should be zero, or, if NUMBER OF BLOCKS is greater than 64512, then the tape device should support variable block size and NUMBER OF BLOCKS should be allowed to set to zero by MODE SELECT.

READ BLOCK LIMITS
The tape drive should report the maximum block length limit using this command.

REPORT DENSITY SUPPORT
PRIMARY DENSITY CODE should be reported. If the tape device supports multiple density values, it should report multiple density support data descriptor blocks.

ASSIGNING ORGANIZATION
This value should be reported. It is used to determine the tape type. Tape drives with one of the following ASSIGNING ORGANIZATION values can be self-identified:

• LTO-CVE
• QUANTUM
• SONY
• STK

REPORT SUPPORTED OPERATION CODES
One_command parameter data format with Command timeouts descriptor should be reported. The commands for which a timeout value should be reported are:

• ERASE
• READ
• WRITE
• SPACE
• LOAD
• REWIND
• INQUIRY