scsi-target and the buffer cache

[Eric Anderson]

Nate Lawson wrote:
> Scott Long wrote:
>> Eric Anderson wrote:
>>
>>> Nate Lawson wrote:
>>>> Agree 100%.  While having it in usermode means there are boundary 
>>>> crossings that increase per-transaction latency, the actual bulk 
>>>> data transfer is via zero-copy IO and you should be able to exceed 
>>>> the data transfer rates of several 10K RPM drives on decent hardware.
>>>
>>> Ok, great.. Now, will scsi_target work ok with raw devices, or only 
>>> files?  (although I'm not sure theres all that much difference really).
>>>
>>
>> You can write your userland code to use whatever files or devices you
>> want.  Are you talking about the scs_target.c code in
>> /usr/share/examples?  That's just a skeletal example that you can use
>> as a starting point for your own work.
>
> No, it's not just a skeletal example.  You can point it at a raw 
> device as the backing store file and it will work as a block device 
> (i.e. RBC command set).  It has been tested as working at least 
> moderately fast over SCSI, FC, and firewire.
>

I'm finally getting around to playing with this, and I'm having some 
problems.  First, I can't seem to make one isp card in target mode and 
the other an initiator.  I've messed with adding the following to 
loader.conf:

hint.isp.0.role="initiator"
hint.isp.1.role="target"

that still doesn't show my currently connected fiber channel devices on 
the initiator side.

I've tried a few different kernel options, currently I have:

options         ISP_TARGET_MODE=1
device          targ

I've also tried just:

options         ISP_TARGET_MODE

and that doesn't seem to allow me to select one either.

Anyhow, I've compiled scsi_target (from 
/usr/share/examples/scsi_target), and tried to run it using a 20gb file 
as the target, and still I can't seem to get it working. 

Is there a doc somewhere I need to read?

Also - as a side note, the Makefile for scsi_target seems like it's 
missing a path variable in order to do a make install, but that's not a 
real issue.


Thanks!
Eric



-- 
------------------------------------------------------------------------
Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
------------------------------------------------------------------------