Date: Tue, 23 Mar 1999 08:56:50 -0500 From: Christophe Dupre <duprec@risq.qc.ca> To: Carlos Carvalho <carlos@fisica.ufpr.br> Cc: AIC7xxx@FreeBSD.ORG Subject: Re: redundancy of SCSI controllers possible? Message-ID: <199903231356.IAA06985@mailboy.risq.qc.ca> In-Reply-To: Your message of "Tue, 23 Mar 1999 10:46:39 -0300." <14071.39743.222524.743833@hoggar.fisica.ufpr.br>
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> I'm talking about writing, not reading. If you have two disks on each > controller, if one controller fails those disks won't be updated, but > the others will. So the info is only partially written, and I'm not > sure the data is there. Or is the raid code smart enough to detect > this? If so, controller failure isn't a problem at all. Then you are right, a controller failure will break the synchronisation. Hopefully, nothing a fsck will not fix. > >> Is it possible to put two controllers on the same bus, and if one of > >> them fails the other keeps with all disks? > > > >IF the aim is to make sure that the box can stay up with single controller > >failure I would make sure I have enough controllers to never put more than > >one disk per RAID set on each controller. > > This isn't possible, there aren't enough PCI slots. Then go with a RAID hardware. If you must have the ultimate redundancy, go with two hardware raids on two controllers, and do a RAID-1 software between them. Make sure the two controllers are on separate PCI bus (high-end servers DO have multiple PCI bus). Also, using a high-end box with, say, 6 PCI slots, you can have 6-disk RAID arrays, with one disk per array on each controller. With the latest 18-gigs disks, it will give a 90-gig array, if using RAID-5, which isn't bad... -- Christophe Dupre Analyste de systemes, RISQ inc. 550 Sherbrooke ouest, suite 250-ouest Tel: (514) 845-7181, ext 237 Montreal, QC CANADA FAX: (514) 845-8083 "Nous ne sommes pas libres de ne pas etre libres, nous sommes obliges de l'etre" - Fernando Savater To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe aic7xxx" in the body of the message
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