From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon McNair Subject: single threaded parity calculation ? Date: Fri, 15 Apr 2011 20:18:48 +0100 Message-ID: <4DA89A18.5010002@mcnair.co.uk> Reply-To: simon@mcnair.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: philip@turmel.org List-Id: linux-raid.ids Hi all, I'm under the impression that the read speed of my 10x1TB RAID5 array is limited by the 'single-threaded parity calculation' ? (I'm quoting Phil Turmel on that and other linux-raid messages I've read seem to confirm that terminology) I'm running an i7 920 with irqbalance but if something is single threaded or single CPU bound I'm wondering what I can do to alleviate it. iostat reports 83MB/s for each disk, running up to 830MB/s for all 10 disks, but the max read speed of the array is approx 256MB/s. Would it be better to have 5 (or more) partitions on each disk, create 5xraid5 arrays (each of which would in theory have a separate thread) and then create a linear array over the top of them to join them together ? yes...I know this is way overthinking and also a potentially dangerous to recreate, but I'm curious what the opinions are. I think I'll probably just end up buying another 1TB drive and making it an 11 disk RAID6 instead. I want maximum space, maximum speed and maximum redundancy ;-). TIA :-) Simon