Date: Thu, 16 Feb 2006 22:37:43 +0000 From: Joao Barros <joao.barros@gmail.com> To: Tom Samplonius <tom@uniserve.com> Cc: Palle Girgensohn <girgen@freebsd.org>, scsi@freebsd.org Subject: Re: NAS w/ multipath Message-ID: <70e8236f0602161437o1593c147na97239cf9054610e@mail.gmail.com> In-Reply-To: <20060214103146.K99735@mgmt.uniserve.ca> References: <2CEE6163475607F32A420FA1@jordgubbe.pingpong.net> <20060207121257.D53605@mgmt.uniserve.ca> <20060214150845.GB29569@in-addr.com> <20060214103146.K99735@mgmt.uniserve.ca>
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On 2/14/06, Tom Samplonius <tom@uniserve.com> wrote: > > On Tue, 14 Feb 2006, Gary Palmer wrote: > > > I suspect higher end devices (e.g. HDS and EMC Symmetrix units) this > > isn't a problem, but in mid range and lower end stuff I'd expect proble= ms > > if the paths landed on separate controllers on the array. > > I don't think this is a problem with current mid-range stuff. A mirro= red > write cache is considered a basic feature. Not only does a mirrored writ= e cache > protect against controller cache consistancy, it also protects losing the > contents of the write cache if a controller fails, which is generally a m= uch > bigger problem. The EMC Clarion Series, at least the CX600 model I work with has mirrored write cache. In the event of controller failure it is disabled until redundancy is resto= red. I had training on an entry level model, a CX300 and the funcionality was the same. The Symetrix I bet it has but EMC doesn't let us touch those ;-) -- Joao Barros
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