Source:Enabling persistent naming for tape devices

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Docs latest icon.png Welcome to the latest SEP sesam documentation version 4.4.3/4.4.3 Tigon. For previous documentation version(s), check Documentation archive.


Overview

Persistent naming or binding is an option that enforces file names for loaders and tape drives, thus making them persist across reboots of the operating system. Without this feature the SCSI addresses may be changed during reboots, especially in environments with several tape libraries attached to a server, and the operating system might mix the SCSI addresses between different loaders and library tape drives. Consequently, SEP sesam may have problems accessing devices, such as unloading incorrect drives, read/open errors, volume errors, lost connections ...

Persistent naming means using symbolic names for loaders, tape drives in autoloaders and tape libraries, as well as for single tape drives. These names stay unique during server reboots, regardless of the order in which the operating system discovers the tape hardware. For example, while Tape0 is a logical name that could change during system restart, the persistent name Tape2147483644 is unique and will not change.

Configuration of persistent naming depends on the used driver.

Information sign.png Note
Persistent naming is not part of SEP sesam as each hardware vendor handles it differently. If you need any assistance, consult your respective OS and hardware vendor support. The following information are only for reference and are not meant to replace the official vendor documentation.

Configuring persistent naming on Windows

To enable persistent bindings of symbolic tape and library names, you have to modify the registry key. Make sure that you have a valid SEP sesam and operating system backup before proceeding!

Standard Windows drivers
For standard Windows drivers, proceed as follows:
  1. Open Registry Editor: use Start and type regedit.
  2. Locate and select the following registry subkey:
  3. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Tape
  4. From the Edit menu, select New and then DWORD Value.
  5. Type Persistence and then press ENTER.
  6. Right-click the Persistence registry entry, then click Modify.
  7. Type 1 in the Value data box, and then click OK.
  8. Close Registry Editor and restart the computer.

When you set the Persistence registry entry to 1, symbolic names become persistent. For example, if your tape drive has the name \\.\\tape1, this name is reserved for use by that device even after your server reboots.

IBM drivers
For IBM drivers, proceed as follows:
  1. Go to
  2. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ibmtp2k<x> where the value <x> in ibmtp2k specifies the Windows Server version, for example, ibmtp2k8 for Windows Server 2008, ibmtp2k12 for Windows 2012, and ibmtp2k16 for Windows 2016, respectively.
  3. Add DWORD:PersistentNaming=1.
  4. Close Registry Editor and ensure that AutoRun is set to 0 for the driver prior to rebooting; for details, see official Microsoft documentation, e.g., Windows Server 2003 cannot perform backup jobs to tape devices on a storage area network or refer to the article Disable Autorun/Autoplay.
  5. Restart the computer.

For more details, see IBM article Configuring drives with persistent naming with IBM devices on Windows.

HP LTO drivers
For HP LTO drivers, follow the procedure as provided by data-protector.org:
  1. Make sure that you have installed the required HP tape drivers.
  2. Copy the following code and insert it into text editor, then save the content as .reg file.
    • Tape drives:
    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\hplto] "AutoRun"=dword:00000000 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Tape] "Persistence"=dword:00000001 [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NtmsSvc] "Start"=dword:00000004
    • Changer:
    [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\MChgr] "Persistence"=dword:00000001
  3. Execute the .reg file and restart the system.

Once OS is configured for persistence naming, update SEP sesam configuration with the help of slu topology.

Configuring persistent naming on Linux

Device persistence on Linux is based on preconfigured udev rules. These rules create aliases in the device filesystem in /dev/tape. The name of the alias is not fixed, but it will remain consistent across reboots on different hosts. For more details, refer to your hardware manufacturer documentation; for example, IBM article Configuring drives with persistent naming for IBM devices on Linux.

See also

Configuring a Loader