NetWorker: Understanding tape library device addressing in NetWorker

Summary: This article describes the procedure to determine what hosts call what physical devices by what name. This information is required for manual library reconfiguration, troubleshooting problems and for some specific scenarios. ...

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Instructions

NetWorker's handling of tape libraries and tape drives relies on its ability to know how to associate the hard drives with the name each Storage Node host knows that drive by.

For example: In a tape library sharing two drives with four storage nodes, the storage nodes may have different operating systems, and even if they are the same, the names each host uses are relevant only to that host, and have no connection whatsoever with the other storage node hosts.

Moreover - it is always possible in Plug 'N Play operating systems like Windows and Linux that the names originally configured in NetWorker have changed due to a hardware, environmental or host-based event. NetWorker's configuration can be invalidated at any time (see Troubleshooting Tape Library Drive Ordering Problems in NetWorker).

This article describes how to test the true physical drive:host:device name associations at any point in time. This is the relationship that must be determined.

Modern method: Using serial numbers
Serial numbers, and the ability for drives and libraries to report them, are ubiquitous in today's tape environment. It is unlikely you will need to use the manual method below.
 

  1. First you will need the address of the library robot from an inquire output from the host which has access to the tape library. This is the three-part number (SCSI address), on the 'Autochanger' entry line:
scsidev@2.1.0:ADIC    Scalar 100      2.62|Autochanger (Jukebox),
WARNING: It is recommended that when multiple hosts access the tape library drives, only a single host can communicate with the library.
  1. Next, using the library robot address, determine the serial number corresponding to each hard drive element (see How to use the NetWorker sjisn tape library command):
Serial Number data for 2.1.0 (ADIC     Scalar 100      ):
        Library:
                Serial Number: 79I9G00200
                SCSI-3 Device Identifiers:
                        ATNN=ADIC    Scalar 100      79I9G00200
        Drive at element address 256:
                SCSI-3 Device Identifiers:
                        VENN=79I9G00201
        Drive at element address 257:
                SCSI-3 Device Identifiers:
                        VENN=79I9G00202
  1. From every Storage Node host who will access library resources, collect an inquire -lcp output (see How to use the NetWorker inquire SCSI discovery command):
scsidev@2.1.0:ADIC    Scalar 100      2.62|Autochanger (Jukebox),
                                           S/N: 79I9G00200
                                           ATNN=ADIC    Scalar 100      79I9G00200
                                           Virtual device
scsidev@2.2.0:IBM     ULTRIUM-TD1     4561|Tape, \\.\Tape2147483646
                                           S/N: 79I9G00201
                                           ATNN=IBM     ULTRIUM-TD1     79I9G00201
                                           Virtual device
scsidev@2.3.0:IBM     ULTRIUM-TD1     4561|Tape, \\.\Tape2147483645
                                           S/N: 79I9G00202
                                           ATNN=IBM     ULTRIUM-TD1     79I9G00202
                                           Virtual device
  1. Using the sjisn output as the element:serial key, and each inquire output as that host's serial:devicename key, draw a grid to represent the mappings:
Example drive mapping chart
Serial number Element Ordering Server Node 1 Node 2 Node 3
79I9G00201 1 \\.\Tape2147483646 /dev/nst3 \\.\Tape5 /dev/tape/by-id/scsi-350060b0036323731-nst
79I9G00202 2 \\.\Tape2147483645 /dev/nst1 \\.\Tape6 /dev/tape/by-id/scsi-350060b0036323730-nst
NOTE: This example uses the inquire and sjisn outputs shown above for the server, and below for Storage Node 3 (others left off for brevity) 
scsidev@1.4.0:IBM     ULTRIUM-TD3     54K1|Tape, /dev/tape/by-id/scsi-350060b0036323731-nst
                                           S/N: 79I9G00201
                                           ATNN=IBM     ULTRIUM-TD3     79I9G00201
                                           WWNN=50060B0036323731
                                           WWPN=50060B0036323731
                                           PORT=00000000
                                           Virtual device
scsidev@1.5.0:IBM     ULTRIUM-TD3     54K1|Tape, /dev/tape/by-id/scsi-350060b0036323730-nst
                                           S/N: 79I9G00202
                                           ATNN=IBM     ULTRIUM-TD3     79I9G00202
                                           WWNN=50060B0036323730
                                           WWPN=50060B0036323730
                                           PORT=00000000
                                           Virtual device
Once this chart is complete, you have your complete device:host:localname map to use as necessary for troubleshooting.

Determining drive addressing in legacy nonserial enabled environments
It is unlikely in today's storage environment that you encounter supported equipment without the ability to report serial numbers (either its own or its elements).
However, it may become necessary to test manually if for one reason or another, serial reporting fails.
WARNING: This method is largely obsolete due to modern technology and tedious and should only be used at need.
  1. Empty all device elements in the library. Use NetWorker if the library is correctly configured; otherwise, use the tape library's own UI or the sjimm and sjirdtag commands.
  2. Load a single volume into the first element and confirm it is the only drive loaded.
  3. Go to each attached storage node in turn and run inquire -lscp to list the available device handles.
  4. Query each device name in turn using cdi_rewind -f {devicename}:
    • No tape present (try next local device name):
CDI_REWIND failed.
cdi_info.status = CDI_CHECK_CONDITION (1)
cdi_info.drivestat is:
status = 10, DRIVE_STATUS_NO_TAPE
msg = There is not a tape in the drive
    • Tapes present (mark this host: device name pair as matching current hard drive, and go to next drive/host):
CDI_REWIND successful.
elapsed time for command was 0 seconds
cdi_info.drivestat is:
status = 0, DRIVE_STATUS_READY
msg = The tape drive is ready for use
  1. Continue in this fashion, building a chart as above, and recording when you find every one of each hard drive's corresponding host: driver name pair.

Additional Information

Affected Products

NetWorker

Products

NetWorker
Article Properties
Article Number: 000010299
Article Type: How To
Last Modified: 30 رمضان 1447
Version:  4
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