Various problems can occur at any location in a SAN. In order for Backup Exec to work properly, a device has to be recognized in three locations; the bridge/router must recognize it as a SCSI device, the operating system must recognize it as a device, and Backup Exec must recognize it as a supported device. In some cases, there will be a problem with your hardware that will require you to contact your hardware vendor for technical support.
You may need to replace a component of your SAN, such as a bridge or hub. For specific steps for replacing your equipment, refer to your hardware vendor’s documentation.
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Troubleshooting offline devices in the SAN Shared Storage Option