Dell PowerVault TL4000 - Manual (Page 10)

Immediately after the user command is finished the media changer switches to on-line mode. Note the
media changer is continuous off-line when it is configured into Sequential Mode.
The concept of control modes is introduced to explain the owner of the media changer. If the media
changer is on-line then the SCSI bus has control of the loader. When the media changer is in OCP Control
mode the OCP has control of the media changer. Described below are the possible control modes of the
library:
v SCSI Control mode (on-line) , in which the media changer is controlled by a SCSI driver issuing
commands to move cartridges between the existing elements. This is the default control mode.
v Sequential mode (off-line), in which the media changer is controlled by the media changers internal
firmware. In this mode the media changer will automatically replace an ejected cartridge from the tape
drive with another one from the media changers inventory. The media changer can be configured into
Sequential mode by means of the OCP menu or RMU browser.
v OCP / RMU / Console Control mode (off-line) , in which the media changer is controlled by a user.
These control modes allow the user to send media access commands like move cartridges between
existing elements.
The media changer will return Not Ready status on media access SCSI command when the media
changer is off-line. The media changer will accept media access SCSI commands when the media
changer is on-line.
About the Not Ready Condition
The media changer reports Not Ready when it is unable to accept medium access commands. During the
Not Ready reason the media changer will perform all non-media access commands as specified.
The media changer is Not Ready when:
v Its initialization routine is in progress
v It is in sequential mode
v It is off-line
v A magazine is removed
Not Ready reason Sense code during Sense info after Not Ready reason finished
Initializing 02/04/01 06/28/00
Magazine removed 02/3B/12 02/04/01 (see note 1)
Sequential Mode 02/04/8E 06/28/00
Off-line 02/04/12 06/28/00
Note: When a magazine is inserted the media changer will automatically re-initialize. During this process
the media changer shall return 02/04/01 status. When initializing is finished the media changer shall
return a unit attention 06/28/00 before returning Ready status.
The following non-media access commands are allowed during the Not Ready reason:
Allowed commands during not ready state
INQUIRY
LOG SENSE
MODE SENSE (6)
MODE SENSE (10)
PERSISTENT RESERVE IN
2-2 TL2000 and TL4000 SCSI Reference