From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <53B596CA.9010407@nellans.org> Date: Thu, 03 Jul 2014 12:45:46 -0500 From: David Nellans MIME-Version: 1.0 Subject: Re: multiple block devices question References: <53B462A3.8050402@kernel.dk> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit To: "Yuyang (Alex) Wang" , Carl Zwanzig Cc: Jens Axboe , "fio@vger.kernel.org" List-ID: On 07/03/2014 12:28 PM, Yuyang (Alex) Wang wrote: > Carl, > > Specifying them as separate jobs will do what I expect. However, in > this case, I am seeking to know how much performance and how many > devices can a __single__ FIO process can drive. If my above > configuration is correct, then, for some reason, the single process > doesn't increase with more devices at its disposal, not as I have seen > from another benchmark tool - which is puzzling. I am curious to > understand why. > > Best, > > A. If you want to benchmark fio throughput or the block layer, not your actual raid array, then use a ramdisk. There are lots of flash devices out there now which will push far more than 1.4GB/s from a single device, rest assured fio isn't your limitation here. 1.4 GB/s with 1M block sizes isn't even 2k IOPS. fio pushes 500k IOPS through the block layer without issue, its not your limiting factor.