Date: Thu, 09 Mar 2006 15:44:54 -0600 From: Eric Anderson <anderson@centtech.com> To: Scott Long <scottl@samsco.org> Cc: freebsd-scsi@freebsd.org, Nate Lawson <nate@root.org> Subject: Re: scsi-target and the buffer cache Message-ID: <4410A1D6.7020400@centtech.com> In-Reply-To: <4410A097.9030709@samsco.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> <440F5141.7010002@centtech.com> <44105A01.5080309@root.org> <44109AEA.5030209@centtech.com> <4410A097.9030709@samsco.org>
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Scott Long wrote: > Eric Anderson wrote: >> Nate Lawson wrote: >> >>> [mailing list changed to scsi@] >>> >>> Eric Anderson wrote: >>> >>>> 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. >>> >>> >>> hints aren't needed. Here's an intro on how to use it: >>> http://root.org/~nate/freebsd/scsi/README.targ >>> >>> The same card is in target or initiator mode based on the >>> scsi_target user program. When it's running, target mode is enabled. >> >> >> Hmm. Then shouldn't a >> >> camcontrol rescan all >> camcontrol devlist -v >> >> show me all the devices on the FC network? If I remove the target >> mode stuff out, and do that, I see all my devices. With it in, I see >> no devices. >> When I run the scsi_target tool (scsi_target -d 0:3:0 /mnt/testfile), >> it shows a bunch of "sending ccb (0x332)" and (0x334) messages >> alternating for a couple hundred lines, then "main loop beginning" >> and a few other messages. If you want the full details, I'd be glad >> to sent them. >> >> Once scsi_target is running, my other FC initiator (FreeBSD 6.1- >> also) can see it. >> >> >>> >>>> 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. >>> >>> >>> There was some debate when I imported it whether to make it an >>> example or usr.sbin. Given the lack of updates (i.e. ki_sig or >>> whatever), I probably should have put it somewhere else. >> >> >> Is it a totally non-supported kind of tool? Is there another option >> for scsi target mode? >> >> >> Thanks! >> Eric >> >> > > Can isp operate as both a target and initiator at the same time? I > thought that that was a pretty rare feature. If not, then when it's in > target mode it won't be able to see any other targets on the bus. That's what I assumed, but docs (man isp I think, and the link posted above by njl) seem to indicate they might. If not, how to I make one target mode, and one an initiator? Thanks! Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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