User's Guide

Chapter 3 Emulated DLT7000 SCSI Commands
Overview of Command and Status Processing
Quantum DX-Series Software Interface Guide 119
The DLT7000 system tape drive recognizes multiple, successive SCSI bus
resets and SCSI bus resets of arbitrarily long duration. The tape drive
recovers within the time limits specified above following the last SCSI
bus reset.
The tape drive goes through a calibration process at power up and
loading of medium.
Data Cache and
Tape Write
Interaction
3
The Quantum DLT7000 system tape drive contains a data cache that
buffers blocks (records) until they are written to tape. This section
describes when those blocks are written, or “flushed” to tape. A Mode
Select parameter allows the data cache to be disabled (unbuffered mode).
In this mode, every WRITE command causes data to be written to the
tape medium before the STATUS byte and the COMMAND COMPLETE
message are returned to the host.
The contents of the write data cache are written to the tape
medium under the following circumstances:
• When two or more WRITE FILEMARKS commands are
issued without intervening tape motion commands.
Note: Unbuffered mode is NOT recommended due to the poor
performance that may result.