Hello, I am trying to understand the passthrough device support of tgt. For a regular block device, to create a LU I use the following command ( I explicitly stated the default values below): tgtadm --mode logicalunit --op new --tid 1 --lun 1 --device-type disk --bstype rdwr --backing-store /dev/sdb The above command takes the block device "/dev/sdb" and exports it as LU 1 to the initiator. - What does it mean the tgt "creates a device of type disk" Creates where, internal to tgt? - What is the implication of that? Is it how the SCSI commands coming over iSCSI is treated/handled (with respect to caching, buffering, read ahead, etct)? Or something else? The following example is cited in the man pages for a passthrough: tgtadm --lld iscsi --op new --mode logicalunit --tid 1 --lun 1 --bstype=sg --device-type=pt --backing-store=/dev/sg4 - How does the "bstype" affect the handling of the SCSI commands? Does this affect how the IO to the actual device is done (manipulated before sending to the actual device)? - What does it mean for the backend storage type to be sg? Really appreciate any help / pointers. Regards, Ahmed. -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
