Specifications

CHAPTER 8 Configuring Devices
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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. Do not enter /dev/st0 or /dev/scd0.
Note: When setting up a generic SCSI device in the virtual machine settings editor,
as described later in this section, you specify the device you wish to install in the
virtual machine by typing its /dev/sg entry in the Connection field.
Requirements
Generic SCSI requires version 2.1.36 of the SCSI Generic (sg.o) driver, which comes
with kernel 2.2.14 and higher.
Avoiding Concurrent Access to a Generic SCSI Device
Under Linux some devices — specifically tape drives, disk drives and CD-ROM drives
— already have a designated /dev entry (traditionally, st, sd and scd, respectively).
When the SCSI Generic driver is installed, Linux also identifies these devices with
corresponding sg entries in /dev — in addition to their traditional entries. GSX
Server ensures that multiple programs are not using the same /dev/sg entry at the
same time but cannot always ensure that multiple programs are not using the
/dev/sg and the traditional /dev entry at the same time. It is important that you
do not attempt to use the same device in both host and guest. This can cause
unexpected behavior and may cause loss or corruption of data.
Permissions on a Generic SCSI Device
You must have read and write permissions on a given generic SCSI device in order to
use the device within a virtual machine, even if the device is a read-only device such
as a CD-ROM drive. These devices typically default to root-only permissions. Your
administrator should create a group with access to read and write to these devices,
then add the appropriate users to that group.