Hot-plugging a device means adding or removing the device without shutting down the operating system or rebooting the system. These devices are also automatically configured or unconfigured without user intervention.
All USB devices are hot-pluggable. However, non-removable USB storage devices are identified as hot-pluggable devices only at the driver level. When these devices are connected or disconnected, the changes caused by automatic configuration or unconfiguration occur at the kernel level and do not affect the use of the devices.
The removable media services manage the mounting of removable media, including hot-pluggable devices. To determine whether the service is running, type the following command:
# svcs hal dbus rmvolmgr STATE STIME FMRI online May_03 svc:/system/dbus:default online May_03 svc:/system/hal:default online May_03 svc:/system/filesystem/rmvolmgr:default
With hot-plugged devices, the file system can be mounted from the device if the device is valid and recognized. While file system mounts occur automatically, you can mount the file system manually if necessary.
Before disconnecting a hot-pluggable device, issue an eject command first. Use the eject –l command to determine the name of the device. Failure to eject before disconnecting the device might damage the device's file system, even though the device itself is released and the port becomes available for use.
When you connect a USB device, the device is immediately added to the system's device hierarchy and is included in the output of the prtconf command.
If you disconnect a device, the device is removed from the system's device hierarchy only if no application is using the device. If an application is using a device that becomes disconnected, the device node remains. However, the driver controlling the device stops all activity on the device. Any new I/O activity issued to this device returns an error. The system then prompts you to connect the original device. If the device is no longer available, stop the application. After a few seconds, the port is released.