Veritas NetBackup™ Commands Reference Guide
- Appendix A. NetBackup Commands
tlhcd — Tape library half-inch (TLH) control daemon (process on Windows systems)
On UNIX systems, the directory path to this command is /usr/openv/volmgr/bin/
On Windows systems, the directory path to this command is <install_path>\Volmgr\bin\
This command applies only to the NetBackup Enterprise Server.
tlhd and tlhcd interface with Media Manager to mount and unmount tape volumes in a tape library half-inch (TLH) robot.
ltid is the Media Manager device daemon on UNIX systems and the NetBackup Device Manager service on Windows systems. tlhd interfaces directly with ltid. tlhd runs on each host with a drive connection and sends mount and unmount requests to the control daemon-process, tlhcd.
tlhcd communicates with the IBM Automated tape library (ATL) library manager, which processes all requests and all control functions for the robotic library. TLH robotic control software permits drives in the same robot to be configured on different hosts. tlhcd can be running on a different host than tlhd, depending on where the IBM library control is configured (see EXAMPLES). When communication with the library is established, tlhd puts the TLH robot in the UP state and can request volume mounts and unmounts. If the library or the control daemon is inaccessible, tlhd changes the robot to the DOWN state. In this state, tlhd is still running and returns the robot to the UP state if tlhcd is able to make a connection.
If drives are on different hosts, enter the robotic information in the Media and Device Management of the Administration Console on all computers. The robot number must be the same on all computers.
On UNIX systems, tlhd and tlhcd automatically start and stop when ltid is started and stopped. To stop or start tlhd independently of ltid, use
/usr/openv/volmgr/bin/vmps or your server's ps command to identify the tlhd process ID. Then enter the following commands:
kill tlhd_pid /usr/openv/volmgr/bin/tlhd [-v] &
The control daemon, tlhcd, is on the host that has the robotic control. tlhcd on that host automatically starts it (see EXAMPLES).
On Windows systems, tlhd and tlhcd are started when the NetBackup Device Manager service is started. They are stopped when this service is stopped. The control process, tlhcd, is on the host that has the robotic control. tlhd starts it automatically on that host (see EXAMPLES). tlhcd stops when you stop the NetBackup Device Manager service.
Before you access any volumes through the NetBackup Device Manager service (Windows systems), ltid, tlhd, and tlhcd, define the following information: the media ID and slot number for volumes in a robot in the EMM database. Both the initial EMM database population and future updates can be accomplished by using Media Manager robotic inventory options.
If a cleaning volume is used, it must be defined in the volume configuration. See tpclean about how to set the frequency to clean the drive automatically.
The drives are configured by using IBM device names. The robotic test utility, tlhtest (robtest if the robot is configured), can be used to determine the device names that are associated with the robot. You can also use this utility along with IBM's mtlib command-line interface to verify library communications, status, and functionality.
Configure the drive cleaning operation for the tape library half-inch robotic control through an IBM library manager console. The cleaning operations are not available to applications that use the IBM library manager. For this reason, you cannot define the volumes to clean through Media Manager. In addition, you cannot use the Media Manager utilities or the tpclean command for cleaning operations on drives under TLH robotic control.
On UNIX systems, the Internet service port number for tlhcd must be in
/etc/services. If you use NIS, place the entry in the
/etc/services file in the master NIS server database for services.
On Windows systems, the Internet service port number for tldcd must be in
The default service port number is 13717.
You must have administrator privileges to run this command.
The following options operate only on UNIX systems.
Logs debug information by using syslogd. If you start ltid with -v, tlhd and tlhcd also start with -v.
tlhd and tlhcd log an error message if a copy of the daemon or process is in operation. Media Manager logs any tape library half-inch and robotic errors to syslogd (UNIX systems) or to the application event log (Windows). Log entries are also made when the state changes between UP and DOWN.
In the following examples the device hosts can be any supported Windows server or the following UNIX servers: AIX, HP-UX, Solaris (SPARC), and Linux.
Example 1 - In the following diagram, the drives are attached to and the robotics are controlled from a single host. ltid initiates tlhd, which in turn initiates tlhcd. lmcpd must be running on Host A. lmcpd is the IBM library manager control-point daemon on UNIX systems and the IBM Automated tape library service on Windows systems.
Example 2 - In the following diagram, each host is connected to at least one drive and the robotics are controlled from Host A. ltid on each computer initiates tlhd. The tlhd on Host A also initiates tlhcd, since that is where the robotic control is defined. Requests to mount tapes from Host B go to tlhd on Host B, which sends the robotic command to tlhcd on Host A.