ATTO Support
Common FibreBridge Issues and Solutions

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SCSI connections:

  • Ensure that all devices are set to different SCSI ID’s, using 0 through 6 and 8 through 15
  • Be sure that the internal termination of the FibreBridge is set correctly
  • Turn power on for all SCSI devices prior to powering the FibreBridge
  • Ensure that all cables are free of damage, and that there are no bent pins on cable ends or terminators. Also check the connections to be sure they are tight and secure
  • Try different cables and terminators. If the problem persists, connect each device individually
  • Check with SCSI device manufacturer for more troubleshooting methods

Bridge configuration:

  • In ExpressNAV or CLI, check to see that all devices are mapped properly
  • Ensure that you are using the correct Fibre Channel data rate. Some devices and host adapters cannot auto negotiate speeds and must be set to 1Gb/2Gb/4Gb manually. Be sure that the speeds are the same for both the device and the FibreBridge
  • Check Fibre Channel settings. Unless the bridge is connected through a Fibre Channel switch, both the bridge and the HBA should be set the same, to PTP or loop. If the bridge is connected through a FC3400 hub, all devices must be set to loop

Fibre Channel connections:

  • Check Fibre Channel cable for cracks, kinks, or other damage. Do not touch the ends of fiber optic cables. Finger prints can distort the signal. Copper cables contain tiny shielded cables which can break internally if flexed excessively.

Q:     My host does not see any of my devices on the FibreBridge

A:   When troubleshooting this kind of problem, the best approach is to troubleshoot using the inside-out method. You begin with the device(s) connected to the bridge first and work your way out.

    SCSI Devices:

    • Check SCSI devices to make sure they are all set to different SCSI ID’s. By default, the FibreBridge SCSI ports use SCSI ID 7. So, drives should use ID’s 0 through 6 and 8 through 15.
    • Check the SCSI device power. Verify that the devices are powering up.
    • Watch the drive lights before, during, and after startup. Many drives have term power lights that should be on before startup and turn off then the system boots.
    • Verify the external terminator is the correct type and does not have damaged pins.
    • Check cable integrity. Check the cables for solid connections and are screwed down. Inspect cable ends for bent or broken pins. If they are only slightly bent, straighten them out with a small screwdriver.
    • If termination is correct, and the problem persists, try drives one at a time with different cables, adding drives and cables until the
    • Verify the FibreBridge has its termination set properly. By default, termination is on full. Instructions to change termination can be found in the Services manual.
    • Either through ExpressNav or CLI, perform a SCSI bus scan on each SCSI port. (e.g. scsitargets 0 (or 1)).
    • problem occurs. This will help pinpoint the drive or cable causing the problem.
    • Check with the manufacturer of your SCSI device(s) for further troubleshooting methods.
    • If the SCSI devices appear to be in working order, move on to the FibreBridge SCSI Side section.

    FibreBridge SCSI Side:

      1. If no devices appear, recheck SCSI cables and termination.

      2. If garbage information appears, the problem is most likely a bad SCSI cable or termination.

      3. Remember, there may be SCSI cabling internal to the SCSI device (like in a JBOD tower or tape library) which should be checked too.

      4. Remember LVD SCSI cable lengths are limited to 12.5 meters max. Longer cables will cause problems. Also, the more drives there are attached, the shorter the maximum cable length. Any internal cable counts toward the total length.

      5. If the SCSI port hangs, the problem is most likely SCSI cabling or termination.

      6. If all devices appear, repeat ‘get scsitargets’ command several times on each SCSI port and verify the devices can still be seen. If devices disappear and come back, again, the problem is most likely a SCSI cable problem.

      7. If all devices appear and remain, move to troubleshooting FibreBridge internals.


    • Some old SCSI devices may improperly negotiate with the FibreBridge SCSI Port. Try changing the FibreBridge SCSI port Speed, Wide Negotiation, and Sync Negotiation settings to match those of the older device. See FibreBridge Services Manual or Users Manual for more details for changing these settings. Remember, when changing any setting on the FibreBridge, the configuration must be saved and firmware restarted by using either ‘saveconfiguration restart’ CLI command or through ExpressNav GUI.

    FibreBridge Internals:

    • Verify that the SCSI devices are mapped properly. Use the ‘routedisplay online’ CLI command to show mappings. Use ‘automap’ command (or older ‘route’ command) to map devices.
    • Remember, when changing any setting on the FibreBridge, the configuration must be saved and firmware restarted by using either ‘saveconfiguration restart’ CLI command or through ExpressNav GUI.

    FibreBridge Fibre Channel Side:

    • Check cable integrity. Check cables for solid connections. If a switch or hub is in the loop, check to see if a valid connection is made. Try swapping cables.
    • If the bridge supports 2-gig operations, make sure the FCDataRate is set to auto.
    • Auto-negotiation between the FibreBridge and switch/hub at the desired speed may not work properly on poorer quality cables and some older switches/hosts. Many times this issue can be resolved by either forcing the host/switch or FibreBridge to the desired speed or replacing the cable.

    Loop/Fabric (PTP):

    • Verify that the hub or switches are zoned properly so that the hosts and FibreBridge have access to each other. If there are existing zones on the switch, the FibreBridge must be added to the zones that require access to the FibreBridge.
    • If there are FC routers (IP to FC for example) involved in the setup, make sure the FibreBridge is allowed access in and out of the router.
    • Verify that the switch can see the FibreBridge on the port(s) in question. See switch vendor’s user’s guide for more information.
    • If using a 2-gig switch, verify that the switch port is set for auto detection of the line speed.
    • Some switches cannot detect and convert loop / fabric login. If your switch is one of those, make sure the FibreBridge is set to the mode the switch supports.

    FC Host Adapter:

    • FC Host Adapters are adapters that appear as a type of storage controller to the host Operating System. Configuration of these adapters is usually done though the vendor’s own utility and not through the OS itself.
    • Check cable integrity.
    • Verify that the hosts are running the recommended driver and firmware level for the FC host adapter.
    • Verify that the host is in the same zone as the FibreBridge.
    • Some adapters do not automatically detect new devices, but have to be manually mapped. Check with the FC adapter vendor for further details.
    • On rare occasions on some older switches, auto negotiation between the host and the switch at the desired speed does not work properly. Many times this issue can be resolved by forcing the host or switch to the desired speed.

    Operating System:

    • Verify that the OS has the required service packs or patches installed.
    • As of this writing, some FC host adapters under certain Operating Systems (like Linux or Solaris) do not always automatically find new targets when plugged in or when a forced rescan is performed. Rebooting the hosts resolves this problem. Also check to see if the vendor has a new driver as well.
    • Some Unix Operating Systems, such as Solaris, need entries in their disk and tape driver configuration files in order for the OS to utilize them, Refer to the OS documentation.
    • Some Operating Systems will not scan for LUNs if no device at LUN 0 is found. Make sure a SCSI device is mapped to LUN 0 on the FibreBridge.

    Applications:

    • Verify that the application is running the latest device drivers for the devices attached to the FibreBridge.
    • Verify with the application vendor if the FC technology is supported on the version of the application being used. Some applications may require a SAN Option in order to operate properly in a FC SAN.

Q:     My host is not getting the desired performance.

A:    Troubleshooting this kind of problem is best performed by the inside-out method. You begin with the device(s) connected to the bridge first and work your way out:

    SCSI Devices:

    • Verify that the devices are running at the highest possible speed the device and bridge supports.

      • 1. Mixing SE and LVD devices on the same SCSI bus will force the speed of the bus to SE, thus slowing faster LVD devices.

      2. FibreBridge will not accelerate an already slow device.


    • Verify that the proper terminator is being used. An SE (Single Ended) terminator will force the SCSI bus to SE speeds.

    SCSI Side of the FibreBridge:

    • Verify that the SCSI port configuration is set to the highest speed. The FibreBridge SCSI port speed, wide negotiation, and sync negotiation settings all affect the speed of the port. By default, these settings are set for optimal speed for the majority of devices.
    • Verify that the SCSI devices are equally distributed between SCSI ports. Optimal performance is seen when only two high-speed SCSI devices (such as SDLT320 or LTO Ultrium-2 tape drives) are connected to each port.

    FC side of the FibreBridge:

    • Verify that the data ports are set to auto negotiate or are set to maximum speed of the device the bridge is connected to. (e.g. if FibreBridge is connected to a 2-gig FC switch, it can be forced to 2-Gigabit speed). Use the CLI command ‘get fcdatarate’ to display the current speed.
    • Verify that FibreBridge TraceLog feature is disabled. Tracelog tracks certain events that occur in the FibreBridge for troubleshooting purposes. With this enabled, performance suffers.

    Loop / Fabric (PTP):

    • Verify that each associated port on the switch / hub is configured for either autodetection or forced to the same line speed.
    • The SAN traffic should be zoned so that each host can only access the desired target devices. (like disk or tape drives)
    • Verify that frames are not being dropped excessively or no frequent line errors occur. Most Fibre Channel switches maintain statistics on these errors as part of their built-in diagnostics.
    • When using a Fibre Channel Hub, bandwidth is shared between all of the ports.

    FC Host Adapter:

    • Verify that the adapter is set to auto negotiate or forced to maximum supported line speed.
    • Set the frame size to the most efficient size for the intended targets. For many tape drives, 64k is the optimal setting. Application:
    • Some applications can be configured to change transfer sizes. Configure the application for the optimal size for the particular SCSI devices connected to the FibreBridge.

    Host System:

    • Verify the FC adapter is connected to the fastest PCI bus connector supported by the adapter.

      • 1. If the adapter supports PCI-X, place the adapter in a PCI-X slot. If one is not available, the host may not achieve the maximum performance capable of the adapter.

      2. Even placing a PCI-X adapter into a 64 bit 66 MHz slot causes loss of performance. Some adapters adjust their clock speed depending on the speed of the PCI slot it is plugged into.


    • The host OS disk and swap disk/partition should be set on a high speed drive such as a SCSI or SATA drive. This minimizes the time needed to access the host’s virtual memory.
    • In general, the more memory a system has, the less time is wasted accessing virtual memory (hard drive space).
    • With all transfers, all data is being read by the host. The faster the host the faster your transfer times will be.
    • The work flow will go only as fast as the slowest connection in the host system. So transferring data from IDE drive, 100 MB Ethernet connection, a DLT 4000, a high speed RAID volume across the country, etc will be slow no matter how fast the rest of the system is.

    Operating System:

    • If possible eliminate the use of swap space, virtual drives, etc. This requires large amounts of system memory. Also, OSs may not allow the elimination of swap space.
    • An OS set to run as many kinds of different servers – file server, web server, email server, database, etc., will be spending much of its CPU cycles on other operations thus slowing down performance.