From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E77E5C4332F for ; Fri, 21 Oct 2022 15:24:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229862AbiJUPYs (ORCPT ); Fri, 21 Oct 2022 11:24:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229882AbiJUPYq (ORCPT ); Fri, 21 Oct 2022 11:24:46 -0400 Received: from mail.bitfolk.com (mail.bitfolk.com [IPv6:2001:ba8:1f1:f019::25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0EAB9402CE for ; Fri, 21 Oct 2022 08:24:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=bitfolk.com ; s=alpha; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:To:From:Date:Sender:Reply-To:Cc:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=r8xqAI8ZnePcnR6uKDR2B5WbKnoX0BGQCcHMDY6BznA=; b=ro6K0EjLhNFfgfny8d8iYjHoCe 33Wn6OofhCqJOK+GCv7iG9YNuYWj7tPsIOUWtsHusZ07wLAN7YGKBuywxZShs7EQdA/uK0l2T8y1i 5BPFlQyI5DQlcWqPt0yy9smKQhbSSm1407muKS3x35L8Rdbk2SOb3e8XPh41CjgVZpMOwTipNj7q6 eAEDIw2IqZFR61+tx2+nFEr+uUmYmxJ60UYgo61G0JQlPEeKoTt4xTjH+bzswCPuOxopMVubWucMr SMxKCWEn5WfRIaop4I/cEZYB11w0pTUm7cTS0g5aBmBdJg8cZ7GTm3/a7P8xnDlNEf792sP22/MpJ PK0bbVUg==; Received: from andy by mail.bitfolk.com with local (Exim 4.89) (envelope-from ) id 1oltsv-0007V1-Rs for linux-raid@vger.kernel.org; Fri, 21 Oct 2022 15:24:33 +0000 Date: Fri, 21 Oct 2022 15:24:33 +0000 From: Andy Smith To: linux-raid@vger.kernel.org Subject: Re: Performance Testing MD-RAID10 with 1 failed drive Message-ID: <20221021152433.jeylw7ynkn4iczyj@bitfolk.com> Mail-Followup-To: linux-raid@vger.kernel.org References:

<7ca2b272-4920-076f-ecaf-5109db0aae46@youngman.org.uk>

<20221021001405.2uapizqtsj3wxptb@bitfolk.com> <6c31fc94-b70e-88c5-205a-efff32baf594@plouf.fr.eu.org> <20221021105107.nhihftkjck74jg6i@bitfolk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: OpenPGP: id=BF15490B; url=http://strugglers.net/~andy/pubkey.asc X-URL: http://strugglers.net/wiki/User:Andy User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: andy@strugglers.net X-SA-Exim-Scanned: No (on mail.bitfolk.com); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Hello, On Fri, Oct 21, 2022 at 06:51:41AM -0500, Roger Heflin wrote: > The original poster needs to get sar or iostat stat to see what the > actual io rates are, but if they don't understand what the spinning > disk array can do fully redundant and with a disk failed it is not > unlikely that the IO load is higher than a can be sustained with a > single disk failed. Though OP is using RAID-10 not RAID-1, and with more than 2 devices IIRC. OP wants to check the performance and I agree they should do that for both the normal case and the degraded case, but what are we expecting *in theory*? For RAID-10 on 4 devices we wouldn't expect much performance hit would we? Since a read is striped across 2 devices and there's a mirror of each so it'll read from the good half of the mirror for each read IO. -- https://bitfolk.com/ -- No-nonsense VPS hosting