Date: Wed, 08 Mar 2006 15:48:49 -0600 From: Eric Anderson <anderson@centtech.com> To: Nate Lawson <nate@root.org> Cc: Scott Long <scottl@samsco.org>, hackers@freebsd.org Subject: Re: scsi-target and the buffer cache Message-ID: <440F5141.7010002@centtech.com> In-Reply-To: <4397EBC7.9030105@root.org> References: <4395BF04.50101@centtech.com> <43960F55.3010508@root.org> <43975926.1010302@centtech.com> <43975F5F.5080901@samsco.org> <439782AA.6000408@root.org> <4397B731.6010308@centtech.com> <4397B82C.5020004@samsco.org> <4397EBC7.9030105@root.org>
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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. ------------------------------------------------------------------------
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