Workstation Pro makes sure that multiple programs do not use the same /dev/sg entry at the same time, but it cannot always ensure that multiple programs do not use the /dev/sg entry and the traditional /dev entry at the same time.
The SCSI generic driver sets up a mapping in /dev for each SCSI device. Each entry starts with sg, for the SCSI generic driver, followed by a number. For example, /dev/sg0 is the first generic SCSI device. Each entry corresponds to a SCSI device in the order specified in /proc/scsi/scsi, from the lowest device ID on the lowest adapter to the highest device ID on the lowest adapter, and so on to the highest device ID on the highest adapter.
Some Linux devices, such as tape drives, disk drives, and CD-ROM drives, already have a designated /dev entry (st, sd, and sr, respectively). When the SCSI generic driver is installed, Linux identifies these devices with corresponding sg entries in /dev, in addition to their traditional entries.
To avoid concurrent access problems, do not specify /dev/st0 or /dev/sr0 when you specify which SCSI device to use in a virtual machine.
