From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: raid1 read io balancing algorithm Date: Thu, 8 Aug 2013 11:27:37 -0300 Message-ID: References: <20130808110452.464E2097@centrum.sk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <20130808110452.464E2097@centrum.sk> Sender: linux-raid-owner@vger.kernel.org To: struhlo@centrum.sk Cc: Linux-RAID List-Id: linux-raid.ids hi, from what i remember, it's done only with device "last position" AKA "disk head position" the device with head position near to position being read is "selected" on sequencial reads, the last used device is used, considering that for sequencial reads a single disk is faster, because we don't waste 3ms to positioning head to sector, that's near true if you don't have diferent devices speed (7200rpm + 10000rpm + 15000rpm + ssd) the best source of this information is source code of raid1.c it's a function (i don't remember the name, but something like read_balancing) sorry many emails the mail list denied HTML emails