From: Akira Fujita Subject: Re: Question of online defrag, thanks Date: Tue, 29 Oct 2013 10:26:02 +0900 Message-ID: <526F0EAA.10401@rs.jp.nec.com> References: <2CE44BD3DBCF9541909CCB42F11CA3921C78E294@sfo1exc-mbxp08.nbttech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: "linux-ext4@vger.kernel.org" , Peng Chen To: Ming Lei Return-path: Received: from TYO200.gate.nec.co.jp ([202.32.8.215]:57799 "EHLO tyo200.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756767Ab3J2BcW (ORCPT ); Mon, 28 Oct 2013 21:32:22 -0400 Received: from tyo201.gate.nec.co.jp ([10.7.69.201]) by tyo200.gate.nec.co.jp (8.13.8/8.13.4) with ESMTP id r9T1WK6r017241 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 29 Oct 2013 10:32:20 +0900 (JST) In-Reply-To: <2CE44BD3DBCF9541909CCB42F11CA3921C78E294@sfo1exc-mbxp08.nbttech.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hello Ming, > During running e4defrag, I am writing/reading data on file system. > Is it safe to use e4defrag? I mean if power failure happens, is there any possibility of data loss or defragging file corruption? # I have received same question from Peng and I already answered him. Anyway; The journal feature and kernel internal locks protect data corruption against power failure and R/W confliction on ext4, so you don't need to worry about that. For more detail about journal, please check the following web page. https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Journal_.28jbd2.29 Regards, Akira Fujita (2013/10/29 2:13), Ming Lei wrote: > Hi, > > I am using e4defrag to defrag running ext4 online. > During running e4defrag, I am writing/reading data on file system. > Is it safe to use e4defrag? I mean if power failure happens, is there any possibility of data loss or defragging file corruption? > If there is possibility of defragging file corruption after power failure, can fsck fix it? > > Thank you very much. > Peng > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >