From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Message-ID: <53F7F22B.1090904@gmail.com> Date: Fri, 22 Aug 2014 20:45:15 -0500 From: Mark Nelson MIME-Version: 1.0 Subject: Re: multiple --name parameters with non-file engine? References: <53F29D76.9080108@gmail.com> <53F7C2C6.7000703@kernel.dk> In-Reply-To: <53F7C2C6.7000703@kernel.dk> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit To: Jens Axboe , fio@vger.kernel.org List-ID: On 08/22/2014 05:23 PM, Jens Axboe wrote: > On 2014-08-18 19:42, Mark Nelson wrote: >> Hi Guys, >> >> I'm using the librbd engine and trying to determine what exactly happens >> when multiple --name parameters are passed. Primarily, I'm wondering if >> each fio process ends up writing to the same blocks on the rbd volume >> during sequential writes. Looking at the code, I see a note that we >> pretend to deal with files even if the engine doesn't understand the >> concept of files: >> >> https://github.com/axboe/fio/blob/master/engines/rbd.c#L405 >> https://github.com/axboe/fio/blob/master/filesetup.c#L1239 >> >> I'm not seeing anything (might be missing it) in the rbd engine or there >> that would partition the volume based on the process though. Am I >> missing anything? > > The same thing will happen as if you ran two instances of fio with the > same options. For rbd, each job will create/connect/open and rbd > instance. For each of these, you can set the rbd pool and clientname. > Thanks Jens. What I'd like to be able to do is start multiple fio processes but have each one only write to a non-overlapping portion of the block device. Preferably I wouldn't have to manually figure out the ranges myself. Any way to do something like that? For now if we are interested in 4MB IOs to RBD we can just do 4MB random as that more or less translates into the same thing behind the scenes in Ceph anyway. Mark