Date: Wed, 10 Oct 2007 09:03:30 -0600 From: Scott Long <scottl@samsco.org> To: Barry Pederson <bp@barryp.org> Cc: freebsd-current@freebsd.org Subject: Re: Are SATA port multipliers supported in -CURRENT? Message-ID: <470CE9C2.4060300@samsco.org> In-Reply-To: <470CDF1D.5050707@barryp.org> References: <46A7B47F.3050300@berkeley.edu> <46A7B607.2070207@samsco.org> <20070927010139.GC22695@eschew.pusen.org> <46FF4E9B.3080104@gneto.com> <470CDF1D.5050707@barryp.org>
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Barry Pederson wrote: > Martin Nilsson wrote: >> Hi, >> >> Have you looked at the Supermicro CSE-836E1 chassis? >> http://www.supermicro.com/products/chassis/3U/836/SC836E1-R800V.cfm >> >> It is also 3U but have space for 16 drives redundant power and the >> computer! The port expander works with the LSI MegaRAID SAS8308ELP >> board and SAS/SATA drives in FreeBSD. There is also a cheaper model >> available with 16 normal SATA connectors if you prefer that. > > I've been pondering this chassis too, and have been wondering how the > FreeBSD mpt driver would react to the builtin SAS expander. I've been > using SAS3041E-R cards (cheaper than the MegaRAIDs) with drives plugged > straight into them very happily. Would that same 4-port card plugged > into a that chassis' expander simply see 16 sata drives as da0..da15? > > It looks like these chassis actually have 28-port expanders, with 4 > ports going in, 16 ports for drives, and 2 4-port groups for > daisy-chaining other chassis. Any idea if another connected chassis > full of drives would just show up as da16..da31 and so on? > There are two possible scenarios here, first is that the controller does a full topology scan and presents the drives to the OS with no OS intervention. Second is that it doesn't do a full scan, and instead presents only the drives that are directly attached. Given that the Linux driver does full discovery itself, I kind of suspect that the latter behavior is what will happen. Full SAS support is on my immediate TODO list, but it's a fairly big project. Scott
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