IBM TS2340 User Guide - Page 200

Control Path Failover Support for Tape Libraries

Page 200 highlights

Windows Device Driver You can find registry subkeys with persistent naming information at HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ibmtpbs2kx Alternately, you can use the Windows Device Manager to examine the device number in order to determine that persistent naming is enabled on your host. Persistent names contain tape device numbers based at 4801101 (which is the decimal equivalent of hexadecimal 0x49424D and ASCII "IBM"). If two physical paths exist to a drive and different Windows device names are required (which happens, for example, when two different HBAs are connected to the drive and Data Path Failover is disabled) the first path discovered claims the persistent device name, and any subsequent paths that connect to the same device receive names according to the order in which they are discovered by the Windows Device Manager. Control Path Failover Support for Tape Libraries To take advantage of Windows Control Path Failover (CPF) support, the appropriate feature code must be installed. Refer to "Automatic Failover" on page 12 for what feature code may be required for your machine type. Configuring and Unconfiguring Control Path Failover Support Control Path Failover support is enabled automatically when the device driver is installed. It may be disabled or reenabled for the entire set of attached medium changers by modifying the registry. 1. Open the reg folder of the driver package. 2. Double click DisableCPF.reg or EnableCPF.reg. 3. Reboot the system. This is necessary for any registry modification to take effect. Querying Primary and Alternate Path Configuration To check if the control path failover has been enabled in the device driver and display the primary and alternate paths, you may use the tape diagnostic and utility tool. Note: Display the primary and alternate path configuration for any device using tape diagnostic and utility functions, refer to Chapter 10, "IBM Tape Diagnostic Tool (ITDT)," on page 259 or "Microsoft Windows System Utility Program (ntutil)" on page 406. Checking Disablement of Control Path Failover Setting If you have disabled the control path failover in device driver's setting by double clicking the DisableCPF.reg file and reboot your system, you may go into the registry by issuing the Windows regedit command to confirm that CPF has been disabled. Look for a line like the following if your system is Windows Server 2003 or Windows Server 2008: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ibmcg2kx] "FailoverDisabled"=dword:00000001 This indicates that CPF has been disabled in the driver. This setting only takes effect after your system is rebooted. 182 IBM Tape Device Drivers Installation and User's Guide

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You can find registry subkeys with persistent naming information at
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ibmtpbs2kx
Alternately, you can use the Windows Device Manager to examine the device
number in order to determine that persistent naming is enabled on your host.
Persistent names contain tape device numbers based at 4801101 (which is the
decimal equivalent of hexadecimal 0x49424D and ASCII "IBM").
If two physical paths exist to a drive and different Windows device names are
required (which happens, for example, when two different HBAs are connected to
the drive and Data Path Failover is disabled) the first path discovered claims the
persistent device name, and any subsequent paths that connect to the same device
receive names according to the order in which they are discovered by the Windows
Device Manager.
Control Path Failover Support for Tape Libraries
To take advantage of Windows Control Path Failover (CPF) support, the
appropriate feature code must be installed. Refer to “Automatic Failover” on page
12 for what feature code may be required for your machine type.
Configuring and Unconfiguring Control Path Failover Support
Control Path Failover support is enabled automatically when the device driver is
installed. It may be disabled or reenabled for the entire set of attached medium
changers by modifying the registry.
1.
Open the
reg
folder of the driver package.
2.
Double click
DisableCPF.reg
or
EnableCPF.reg
.
3.
Reboot the system. This is necessary for any registry modification to take effect.
Querying Primary and Alternate Path Configuration
To check if the control path failover has been enabled in the device driver and
display the primary and alternate paths, you may use the tape diagnostic and
utility tool.
Note:
Display the primary and alternate path configuration for any device using
tape diagnostic and utility functions, refer to Chapter 10, “IBM Tape
Diagnostic Tool (ITDT),” on page 259 or “Microsoft Windows System -
Utility Program (ntutil)” on page 406.
Checking Disablement of Control Path Failover Setting
If you have disabled the control path failover in device driver’s setting by double
clicking the
DisableCPF.reg
file and reboot your system, you may go into the
registry by issuing the Windows
regedit
command to confirm that CPF has been
disabled. Look for a line like the following if your system is Windows Server 2003
or Windows Server 2008:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ibmcg2kx]
"FailoverDisabled"=dword:00000001
This indicates that CPF has been disabled in the driver. This setting only takes
effect after your system is rebooted.
Windows Device Driver
182
IBM Tape Device Drivers Installation and User’s Guide