From mboxrd@z Thu Jan 1 00:00:00 1970 From: Curt Hartung Subject: Stupid question regarding RAID-1 access pattern Date: Wed, 06 Jan 2010 14:58:16 -0500 Message-ID: <4B44EB58.2090400@northarc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: "linux-raid@vger.kernel.org" List-Id: linux-raid.ids Tried to ferret out the answer to this myself and so far so bad. This just 'popped in there' while I was optimizing something completely different... in a RAID-1, writes have to be mirrored of course, thats what RAID-1 is, but for reads, could they not be sped up by a significant amount if a storage pattern was chosen such that large blocks of data were "striped" in an in-order/out-of-order scheme? In other words, store all the data on both drives, but in huge (2x cache size) -ish blocks that might allow 50% of a given [large] access to come from each drive, with trivial [smaller] reads always coming from one or the other chosen at random. Downside, I know, is that the data would be organized ina way only the raid subsystem would understand, so the niceness of pulling a mirrored drive out of service and it being a literal copy of the otehr drive would be lost, but for such a speedup I'd be willing to pay the price of always having to access it as a failed set (worst case) through the md-daemon. Am I off into the weeds? -Curt