From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Nelson Subject: Re: 10 times higher disk load with btrfs Date: Mon, 05 Jan 2015 14:29:00 -0600 Message-ID: <54AAF40C.3060608@redhat.com> References: <54AAD9B5.5080207@profihost.ag> <54AAE3BF.9080908@profihost.ag> <54AAF1FA.9040709@profihost.ag> Reply-To: mnelson@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-qg0-f45.google.com ([209.85.192.45]:59872 "EHLO mail-qg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752918AbbAEU3E (ORCPT ); Mon, 5 Jan 2015 15:29:04 -0500 Received: by mail-qg0-f45.google.com with SMTP id z107so4711204qgd.4 for ; Mon, 05 Jan 2015 12:29:03 -0800 (PST) In-Reply-To: <54AAF1FA.9040709@profihost.ag> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Stefan Priebe , Sage Weil Cc: ceph-devel@vger.kernel.org On 01/05/2015 02:20 PM, Stefan Priebe wrote: > Hi Sage, > > Am 05.01.2015 um 20:25 schrieb Sage Weil: >> On Mon, 5 Jan 2015, Stefan Priebe wrote: >>> >>> Am 05.01.2015 um 19:36 schrieb Stefan Priebe: >>>> Hi devs, >>>> >>>> while btrfs is now declared as stable ;-) i wanted to retest btrfs on >>>> our production cluster on 2 out of 54 osds. So if they crash it doesn't >>>> hurt. >>>> >>>> While if those OSDs run XFS have spikes of 20MB/s every 4-7s. The same >>>> OSDs after formatting them with btrfs have spikes of 190MB/s every >>>> 4-7s. >>>> >>>> Why does just another filesystem raises the disk load by a factor of >>>> 10? >>> >>> OK this seems to happen cause ceph is creating every 5s a new >>> subvolume / >>> snap. Is this really expected / needed? >> >> You can disable it with >> >> filestore btrfs snap = false >> >> I'm curious how much this drops the load down; originally the >> snaps were no more expensive than a regular sync but perhaps this >> has changed... > > - with XFS the average write is at 9Mb/s > - with btrfs (filestore_btrfs_snap=true) write is at 40Mb/s > - with btrfs (filestore_btrfs_snap=false) write is at 20Mb/s Is that the average and not the spikes? It looks like before the spikes were 20MB/s and 190MB/s? > > Stefan > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html