From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from postfix.iai.uni-bonn.de ([131.220.8.4]:52163 "EHLO postfix.iai.uni-bonn.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751353AbaBTL0y (ORCPT ); Thu, 20 Feb 2014 06:26:54 -0500 Message-ID: <5305E63B.4000405@informatik.uni-bonn.de> Date: Thu, 20 Feb 2014 12:25:47 +0100 From: Sebastian Ochmann MIME-Version: 1.0 To: wangsl.fnst@cn.fujitsu.com Cc: linux-btrfs@vger.kernel.org Subject: Re: Meaning of \"no_csum\" field when scrubbing with -R option References: <5305DE1E.8080302@cn.fujitsu.com> In-Reply-To: <5305DE1E.8080302@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello, > Sebastian Ochmann posted on Wed, 19 Feb 2014 13:58:17 +0100 as excerpted: > > > So my question is, why does scrub show a high (i.e. non-zero) value for > no_csum? I never enabled nodatasum or a similar option. > > Did you enable nodatacow option? if nodatacow option is enabled, > data checksums will be also disabled at the same time. No, never, not even on single files. Some additional info: The filesystem is only a few weeks old (even though I see similar results on an older filesystem as well), it's my root filesystem, and as mount options I use "rw,noatime,ssd,discard,space_cache" (it's on a SSD). Kernel version is 3.12.9. Best regards, Sebastian