From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 19DC37F4E for ; Mon, 20 Oct 2014 03:00:45 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay3.corp.sgi.com (Postfix) with ESMTP id A68C9AC001 for ; Mon, 20 Oct 2014 01:00:41 -0700 (PDT) Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by cuda.sgi.com with ESMTP id 9UR18FAmQuseAy6i (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Mon, 20 Oct 2014 01:00:36 -0700 (PDT) Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by gateway2.nyi.internal (Postfix) with ESMTP id 220D1205D2 for ; Mon, 20 Oct 2014 04:00:36 -0400 (EDT) Message-ID: <5444C122.4080104@fastmail.fm> Date: Mon, 20 Oct 2014 10:00:34 +0200 From: Bernd Schubert MIME-Version: 1.0 Subject: Re: Problem about very high Average Read/Write Request Time References: <20141018143848.3baf3266@galadriel.home> <21571.36364.518119.806191@tree.ty.sabi.co.uk> In-Reply-To: <21571.36364.518119.806191@tree.ty.sabi.co.uk> 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: Peter Grandi , Linux fs XFS On 10/19/2014 12:10 PM, Peter Grandi wrote: >>> I am using xfs on a raid 5 (~100TB) and put log on external >>> ssd device, the mount information is: /dev/sdc on >>> /data/fhgfs/fhgfs_storage type xfs >>> (rw,relatime,attr2,delaylog,logdev=/dev/sdb1,sunit=512,swidth=15872,noquota). >>> when doing only reading / only writing , the speed is very >>> fast(~1.5G), but when do both the speed is very slow (100M), >>> and high r_await(160) and w_await(200000). > >> What are your kernel version, mount options and xfs_info output ? > > Those are usually important details, but in this case the > information that matters is already present. > > There is a ratio of 31 (thirty one) between 'swidth' and 'sunit' > and assuming that this reflects the geometry of the RAID5 set > and given commonly available disk sizes it can be guessed that > with amazing "bravery" someone has configured a RAID5 out of 32 > (thirty two) high capacity/low IOPS 3TB drives, or something > similar. > > It is even "braver" than that: if the device name > "/data/fhgfs/fhgfs_storage" is dedscriptive, this "brave" > RAID5 set is supposed to hold the object storage layer of a > BeeFS highly parallel filesystem, and therefore will likely > have mostly-random accesses. > Where do you get the assumption from that FhGFS/BeeGFS is going to do random reads/writes or the application of top of it is going to do that? Bernd _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs