Date: Wed, 29 Mar 2000 15:24:09 +1000 (EST) From: Carl Makin <carl@xena.aipo.gov.au> To: Matthew Jacob <mjacob@feral.com> Cc: current@FreeBSD.ORG Subject: Re: Dual Pathing to SCSI/FC devices. Message-ID: <Pine.BSF.4.21.0003291514240.91113-100000@newton.aipo.gov.au> In-Reply-To: <Pine.BSF.4.10.10003281712180.1744-100000@beppo.feral.com>
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On Tue, 28 Mar 2000, Matthew Jacob wrote: > Umm, okay. Is this with Veritas DMP or VCS? Good question. DMP I think. I'm not sure what VCS is. > 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 There doesn't seem much point in using VINUM with an external RAID5 box (although we use VINUM a lot on other machines). > 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. Would it be hard to add intelligence to this layer that would detect if a drive (via it's VPD info) is visible on multiple busses? If so is there a point in CAM where it could be modified to handle, at the minimum, a redundant path or better yet, use multiple paths to a device? The box to which I'm hooking this up has sufficient performance to handle 16 U2W SCSI links running hard. Being able to utilise multiple paths could be a big performance win. > 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. I have a Qlogic 2200 on order to test this out. > 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 Would this be similar to the situation that we had with FreeBSD before you could wire down devices? > Let me know if this is enough info to help. I'm getting a little beyond my depth in CAM internals here. But it is *very* interesting. :) Thanks, Carl. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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