From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id E7CB97F47 for ; Wed, 24 Sep 2014 11:18:22 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay1.corp.sgi.com (Postfix) with ESMTP id C7E6A8F8039 for ; Wed, 24 Sep 2014 09:18:19 -0700 (PDT) Received: from sandeen.net (sandeen.net [63.231.237.45]) by cuda.sgi.com with ESMTP id Ldo6vJ5Kmyp0BW7H for ; Wed, 24 Sep 2014 09:18:17 -0700 (PDT) Message-ID: <5422EECA.10301@sandeen.net> Date: Wed, 24 Sep 2014 11:18:18 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: Re: How to format RAID1 correctly References: <5422146A.90206@evermeet.cx> <54222763.40107@sandeen.net> <5422285B.6010306@evermeet.cx> <542234F6.4080000@hardwarefreak.com> <5422376D.3000204@evermeet.cx> <542243E6.1040302@hardwarefreak.com> <5422E912.1000708@evermeet.cx> In-Reply-To: <5422E912.1000708@evermeet.cx> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Helmut Tessarek , Stan Hoeppner , xfs@oss.sgi.com On 9/24/14 10:53 AM, Helmut Tessarek wrote: > On 2014-09-24 0:09, Stan Hoeppner wrote: >> If you create any striped arrays, especially parity arrays, with md make >> sure to manually specify chunk size and match it to your workload. The >> current default is 512KB. This is too large for a great many workloads, >> specifically those that are metadata heavy or manipulate many small >> files. 512KB wastes space and with parity arrays causes RMW, hammering >> throughput and increasing latency. > > Thanks again for the valueable information. > > I used to work with databases on storage subsystems, so placing GBs of > database containers for tableapaces on arrays with a larger stripe size > was actually beneficial. > For log files and other data I usually used different cache settings and > strip sizes. > > So how does this work with SW RAID? > > Does the XFS chunk size equal the amount of data touched by a single r/w > operation? It has more to do with where allocations start, so that allocations don't cross stripe boundaries if possible. -Eric _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs