From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Soltys Subject: Re: chunk size (was Re: Time to deprecate old RAID formats?) Date: Tue, 23 Oct 2007 21:21:54 +0200 Message-ID: <471E49D2.9070608@ziu.info> References: <18200.49267.763509.924873@stoffel.org> <18200.53593.687483.120827@stoffel.org> <1192810534.1666.68.camel@firewall.xsintricity.com> <18200.56684.14194.630264@stoffel.org> <18200.57042.989520.666476@stoffel.org> <1192813477.1666.74.camel@firewall.xsintricity.com> <1192814581.1666.87.camel@firewall.xsintricity.com> <47193314.5010606@ziu.info> <1192886944.1666.124.camel@firewall.xsintricity.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1192886944.1666.124.camel@firewall.xsintricity.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: Doug Ledford List-Id: linux-raid.ids Doug Ledford wrote: > > Well, first I was thinking of files in the few hundreds of megabytes > each to gigabytes each, and when they are streamed, they are streamed at > a rate much lower than the full speed of the array, but still at a fast > rate. How parallel the reads are then would tend to be a function of > chunk size versus streaming rate. Ahh, I see now. Thanks for explanation. I wonder though, if setting large readahead would help, if you used larger chunk size. Assuming other options are not possible - i.e. streaming from larger buffer, while reading to it in a full stripe width at least. > > I'm not familiar with the benchmark you are referring to. > I was thinking about http://www.mail-archive.com/linux-raid@vger.kernel.org/msg08461.html with small discussion that happend after that.