From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: Low cost PCI-E unRAID - Supermicro AOC-SASLP-MV8 Driver/LBA questions for HW owners/users Date: Sun, 23 Jan 2011 19:52:57 -0600 Message-ID: <4D3CDB79.4000100@hardwarefreak.com> References: <4D39D8B5.1090901@hardwarefreak.com> <4D3B0009.6020006@hardwarefreak.com> <4D3B7B2C.5040003@hardwarefreak.com> <4D3C64CB.2080002@harddata.com> <4D3C9C94.8090607@hardwarefreak.com> <4D3CB72E.3050000@harddata.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4D3CB72E.3050000@harddata.com> Sender: linux-raid-owner@vger.kernel.org To: Maurice Hilarius , Linux RAID List-Id: linux-raid.ids Maurice Hilarius put forth on 1/23/2011 5:18 PM: > On 1/23/2011 2:24 PM, Stan Hoeppner wrote: >> .. >>> Chenbro backplanes do not support 6Gb SAS/SATA. >> Considering no single (mech) drive can push 600 MB/s, let alone 300 MB/s, is >> this really an issue? > Yes. > I have seen it first hand. > If you connect 6GB drives and interfaces to it, you see a lot of errors. > One has to be careful to set all devices to 3GB, assuming the devices have > jumpers or other means to do so. Which chassis model was this? >> Mech drives aren't even going to be surpassing 300 MB/s >> in the foreseeable future. >> > Perhaps, but their buffers do, and if one uses expanders it is useful The _real world_ application performance difference between SATA II and SATA III mech drive interfaces is something on the order of 1%. With SSDs a little more as some of them can actually push data faster than 3 Gb/s. Upstream of an expander the additional b/w is useful, not downstream. -- Stan