From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.fusionio.com ([66.114.96.30]:36874 "EHLO mx1.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754521Ab1ESH7E (ORCPT ); Thu, 19 May 2011 03:59:04 -0400 Message-ID: <4DD4CDC3.3000909@fusionio.com> Date: Thu, 19 May 2011 09:58:59 +0200 From: Jens Axboe MIME-Version: 1.0 Subject: Re: fio accessing boot drive References: In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Vikram Seth Cc: Josh Aune , "fio@vger.kernel.org" On 2011-05-19 03:50, Vikram Seth wrote: > Hi Josh, > > Thanks for the response. > > Do you mean use 'norandommap' option ? > If I disable random map then won't I lose coverage on random i/o testing? You will. With the random map turned out, you are guarenteed to hit every block and only once. Without it, you are at the mercy of the random number generator. But it is of high quality, so coverage will still be excellent and it'll likely be faster (and retain randomness at the end of the run, the random map tends to give up at the very end). Unless you are absolutely needing the coverage guarentee, I would just turn it off if it's a problem. Alternatively, make /tmp a tmpfs or similar so updates to the maps don't end up touching disk. -- Jens Axboe