The Linux SCSI Generic (sg) HOWTO
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8.15. SG_SCSI_RESET

SG_SCSI_RESET 0x2284. Assumes 3rd argument points to an int. That int should be one of the following defined in the sg.h header:

SG_SCSI_RESET_NOTHING (0x0): can be used to poll the device after a reset has been issued to see if it has returned to the normal state. If it is still being reset or it is offline then EBUSY will be placed in errno,
SG_SCSI_RESET_DEVICE (0x1): issues a reset to the SCSI device associated with the current sg file descriptor,
SG_SCSI_RESET_BUS (0x2): issues a reset to the SCSI bus that contains the device associated with the current sg file descriptor. This will usually have an adverse effect on any other SCSI device sharing this SCSI bus, especially if it was in the middle of an operation,
SG_SCSI_RESET_HOST (0x3): issues a reset to the host that controls the SCSI bus that contains the device associated with the current sg file descriptor. This operation can have an adverse effect on any SCSI device that is connected to this host.

The reset options are in ascending order of severity. Not all levels are supported by all linux lower level drivers. Most lower level (adapter) drivers support the SCSI bus reset. These boards often issue a SCSI bus reset during their initialization.

Unfortunately this ioctl() doesn't currently do much (but may in the future after other issues are resolved). Yields an EBUSY error if the SCSI bus or the associated device is being reset when this ioctl() is called, otherwise returns 0. N.B. In some recent distributions there is a patch to the SCSI mid level code that activates this ioctl. Check your distribution.

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