Date: Wed, 25 Feb 1998 05:54:20 -0800 (PST) From: asami@FreeBSD.ORG (Satoshi Asami) To: tom@sdf.com Cc: blkirk@float.eli.net, hackers@FreeBSD.ORG, scsi@FreeBSD.ORG Subject: Re: SCSI Bus redundancy... Message-ID: <199802251354.FAA18637@silvia.HIP.Berkeley.EDU> In-Reply-To: <Pine.BSF.3.95q.980224212624.12581J-100000@misery.sdf.com> (message from Tom on Tue, 24 Feb 1998 21:29:27 -0800 (PST))
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(Redirected to -scsi) * SCSI adapter rarely fail. I've seen one that fried itself. Adaptec 3940UW (the fried chip was actually the PCI-PCI bridge). * It is possible to have up to two host adapters per channel. Yes. We've tried it before, with a couple of patches from Justin (since merged to the main source), we could get it to work. (The same single-ended controllers as above.) * Someone the freebsd-scsi list is working on this. Rather than a simple * backup design, he is working on simultanous use of both host adapters at * the same time, by two separate computers. The two systems communicate to * make sure they don't step on each others toes when accessing the disks. * The idea is to make a fully fault-tolerant cluster. We're working on something similar, although not as extensible as what you described. The plan is to have all disks mounted read-only from both systems during normal operation. When there is a write, it first gets unmounted from one machine before it gets written on the other. Note we haven't actually done anything about this (except making sure both systems boot and we can at least get disks to work if we only mount it from one system at a time). Satoshi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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