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Read Command
• If a filemark is encountered, Check Condition status is returned, the filemark
• If end-of-data is encountered, Check Condition status is returned, the Sense
• A Read past the logical end-of-tape (LEOT) does not generate a Check
• After a Read command, the drive continues reading records into the buffer
• A transfer length of zero will not transfer any data, does not generate Check
Data Integrity Validation—Read Operations
During read operations when DIV mode is enabled, all Read commands should have
a transfer length that includes both the user data and the appended 4 bytes of
Protection Information.
When in DIV mode the T10000 A and B tape drives generate the PI data as it is being
transferred from the tape drive to the controller data buffer.
On T10000C and T10000D tape drives the PI data is read from the media and
transferred to the controller data buffer.
If an error occurs during Read operations, and the drive detects a miscompare, it
reports it as a:
Check condition, with
Key = 04h (Hardware Error), and
ASC/ASCQ = 10 01h — Logical Block Guard Check Failed
Examples of when this may occur include:
• During the transfer of data from the tape drive to the controller data buffer,
PI data is generated or checked as required.
• During the transfer of data from the controller data buffer to the Fibre Channel
Port protocol chip, if it supports the current PI method.
• If the transfer length is more than the actual user data plus the PI bytes the tape
drive returns all available user data and the PI bytes, reporting an Illegal Length
Indicator (ILI).
• If the transfer length is less than the actual user data plus the PI bytes the tape
drive checks the entire record in the controller data buffer against the PI bytes.
Then reports a PI miscompare if necessary.
142 T10000: Interface Reference Manual
and valid bits in sense data are set, and tape is positioned after the file mark. In
variable block mode the Information bytes are set to transfer length. In fixed
block mode, Information bytes are set to transfer length minus the actual
number of blocks read, not counting the filemark.
Key is set to Blank Check, and the valid bit is set. Tape is positioned after the
last valid record. Information Bytes are calculated as for a file mark.
Condition. Reading into the physical end-of-tape (PEOT) generates Check
Condition status with a sense key indicating Medium Error.
until the buffer is full or end of data or consecutive filemarks are found.
Reading ahead allows faster response to subsequent Read commands.
Condition status, and does not change the position of the tape.
Note – Use the Mode Select command Page 0Ah, Subpage F0h, to
enable the DIV mode.
August 2016
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