/sys/class/scsi_host/host*/rescan
The host rescan attribute is a write-only attribute. Writing to this attribute will cause the driver to scan for new, changed, or removed devices (e.g., hot-plugged tape drives, or newly configured or deleted logical volumes) and notify the SCSI mid-layer of any changes detected. Usually this action is triggered automatically by configuration changes, so the user should not normally have to write to this file. Doing so may be useful when hot-plugging devices such as tape drives or entire storage boxes containing pre-configured logical volumes.