Date: Tue, 28 Mar 2000 17:20:51 -0800 (PST) From: Matthew Jacob <mjacob@feral.com> To: Carl Makin <carl@xena.IPAustralia.gov.au> Cc: current@FreeBSD.ORG Subject: Re: Dual Pathing to SCSI/FC devices. Message-ID: <Pine.BSF.4.10.10003281712180.1744-100000@beppo.feral.com> In-Reply-To: <Pine.BSF.4.21.0003291049440.91113-100000@newton.aipo.gov.au>
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> On Tue, 28 Mar 2000, Matthew Jacob wrote: > > > Yes, we very much has considered this. What's your issue about this, per se? > > Well, the driver for asking was my management asking if FreeBSD supported > this, as we're going to do it on AIX (with the Dual Pathing Option) and > with Solaris (running Veritas which I need to investigate more). We're > reasonably big on redundancy here and we're running a number of critical > systems on FreeBSD (DNS, WINS, DHCP, primary webserver, PDF server, etc). Umm, okay. Is this with Veritas DMP or VCS? > > > Right now there's no framework code to directly exploit or prohibit multiple > > paths to the same disk, whether via Fibre Channel or SCSI. > > Ok, but I suspect it would get a trifle upset if I started duplicating > LUNS. :) I really don't know how much work this would be but would be > interested in helping. No, it wouldn't get upset, but it wouldn't know to not get upset either :-). Formally speaking, the current non-cognizant arrangement of FreeBSD would be an active-active configuration. If you use Greg Lehey's VINUM in FreeBSD, I'm not clear about what it's role in terms of recognizing redundant paths might be, but other than that there are no particular volume or spindle identification restrictions that could cause an upset. The CAM midlayer does track Vital Product Data (like drive serial numbers), but this is put together with a bus address (e.g, HBA, bus on HBA, target, lun) to track whether particular device has changed at that location or not- not whether that particular spindle is replicated elsewhere. > > I'm not a kernel hacker but I can offer testing resources (well, in about > a month or so when the box arrives) for SCSI and possibly Fibre Channel if > someone has code. Absolutely. I mean, we do have a supported Fibre Channel card (Qlogic 2100 and Qlogic 2200), but not as much testing as one would like. You should note that there isn't, for fibre channel, any particular address wiring enforced except by that which the target device does (e.g., if the target does hard loop addressing). I've been mulling over some persistent device attribute stuff for the next round of changes (e.g., binding a particular WWN to a particular 'target'), probably stored in card NVRAM, and I've had on my 'futures' list a 'WWN' extension to devfs, but this is all futures. Let me know if this is enough info to help. -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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