Dan Bar Dov wrote:
On 4/10/06, FUJITA Tomonori <[EMAIL PROTECTED]> wrote:
The OLS abstract may be more informative.
http://www.linuxsymposium.org/2006/view_abstract.php?content_key=19
Is the full document available as well?
The code is shorter than the paper.
In short, tgt is the framework for SCSI target drivers. The
combination of tgt and the iSCSI target driver for NIC provides the
similar features that IET does.
SCSI targets are LLDs that sit below the mid-layer. iSCSI target on
the other hand is a "network" protocol driver, that sits above SCSI
(sd, st, sg, or directly over mid-layer). Seems like you'd need two
different frameworks, no?
tgt/stgt is probably two frameworks from your point of view. There is a
kernel part for target LLDs to hook into. The kernel part is similar to
scsi-ml, actually it builds onto it and uses some of the scsi-ml
functions, and provides code to share for tasks like creating scatter
lists and mapping commands between the kernel and userspace. The target
LLD basically handles lower level issues like DMAing the data, transport
issues, etc, pretty much what a scsi-ml initiator driver does. For
iscsi, the tgt lld performs similar tasks as the initiator. It parses
the iscsi PDUs or puts them on the interconnect, handles session and
connection manamgement (this would be done like open-iscsi though), but
then then passes the scsi command to tgt's kernel code.
The other part of the framework is the userspace component. The tgt
kernel component basically passes scsi commands and task management
functions to a userspace daemon. The daemon contains the scsi state
machine and execute the IO. When it is done it informs the the kernel
component which in turn maps the data into the kernel, forms scatter
lists, and then passes them to the target LLD to send out.
_______________________________________________
openib-general mailing list
[email protected]
http://openib.org/mailman/listinfo/openib-general
To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
