Sun StorageTek L700 Tape Library
 
Sun StorageTek L180 Tape Library
 

GCS>Sun Microsystems>Storage - Tape>Libraries - L-Series
 

Applies to:

Goal

This is especially the case when sharing tape drives between multiple hosts (so-called SAN storage nodes or SAN media servers) because the drive's WWN changes and both the SAN switch and the HBA bindings may need to be altered. Sometimes, even the application needs to be reconfigured. All this can be avoided on L180and L700 tape libraries when applying dynamic WWN's.

Solution

Previously, Fibre Channel devices contained fixed Worldwide names within the network. If a defective tape drive required replacement, the new device was detected by the network as "unknown" and reconfiguration of the network was required.
When enabled, dWWN assigns names to library drive slots rather than devices. When a drive is replaced, the new drive receives the same name as the one replaced, thereby eliminating the need for system
reconfiguration.
There are three Worldwide Names reserved for each drive: Node, Port A, and Port B.
Enabling dWWN:
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The dWWN feature (default set to OFF) is enabled through the CLI interface and, once enabled, the library must be IPL'd.

CAUTION: System problems: Changing the dWWN feature must be coordinated with the system administrator. The feature is usually enabled at installation time. A record of the configuration should be kept. This is something that should always be done, but it is absolutely essential with the dWWN feature to
eliminate system issues in the case of an MPC/MPCL failure.
When the dWWN feature is enabled, all FC tapedrives in the library are given a generated dWWN. You cannot partially mix dWWN FC tapes drives and FC tape drives with their own WWN.
The dWWN is built off of the Library serial number that is manually entered through the CLI port when the MPC card is installed or replaced.
There are complete instructions on what to do when the MPC gets replaced and how to reconfigure the replacement to support the dWWN. The drives will NOT be assigned a new dWWN, which completely eliminates the need to reconfigure the switch (eg., WWN based zones), the Solaris OE (eg., persistent binding on JNI adapters), or the application (eg.,the NBU sg driver).
Note: This feature requires a corresponding drive code that supports it.
Currently, IBM LTO drive firmware 27Q1 is the only available supporting code. Firmware for other drives is in process and will be released with the next drive firmware versions.

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