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Wed, 19 Jul 2023 12:51:41 +0200 (CEST) Received: from [192.168.3.20] (helo=tomerius.de) by jukebox.tomerius.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1qM4mS-0005X8-JQ; Wed, 19 Jul 2023 12:51:40 +0200 Date: Wed, 19 Jul 2023 12:51:39 +0200 From: Kai Tomerius To: Theodore Ts'o Message-ID: <20230719105138.GA19936@tomerius.de> References: <20230717075035.GA9549@tomerius.de> <20230718053017.GB6042@tomerius.de> <20230718213212.GE3842864@mit.edu> MIME-Version: 1.0 In-Reply-To: <20230718213212.GE3842864@mit.edu> User-Agent: Mutt/1.10.1 (2018-07-13) X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Mailman-Approved-At: Thu, 20 Jul 2023 06:33:33 +0000 Subject: Re: [dm-devel] File system robustness X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?iso-8859-1?Q?Bj=F8rn?= Forsman , dm-devel@redhat.com, Ext4 Developers List , "Alan C. Assis" , linux-embedded@vger.kernel.org Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: tomerius.de Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit > In answer to Kai's original question, the setup that was described > should be fine --- assuming high quality hardware. I wonder how to judge that ... it's an eMMC supposedly complying to some JEDEC standard, so it *should* be ok. > ... if power is cut suddenly, the data used by the Flash > Translation Layer can be corrupted, in which case data written months > or years ago (not just recent data) could be lost. At least I haven't observed anything like that up to now. But on another aspect: how about the interaction between dm-integrity and ext4? Sure, they each have their own journal, and they're independent layers. Is there anything that could go wrong, say a block that can't be recovered in the dm-integrity layer, causing ext4 to run into trouble, e.g., an I/O error that prevents ext4 from mounting? I assume tne answer is "No", but can I be sure? Thx regards Kai -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kai Tomerius Subject: Re: File system robustness Date: Wed, 19 Jul 2023 12:51:39 +0200 Message-ID: <20230719105138.GA19936@tomerius.de> References: <20230717075035.GA9549@tomerius.de> <20230718053017.GB6042@tomerius.de> <20230718213212.GE3842864@mit.edu> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1689763901; s=strato-dkim-0002; d=tomerius.de; h=In-Reply-To:References:Message-ID:Subject:Cc:To:From:Date:Cc:Date: From:Subject:Sender; bh=lvLGZstJ8wKorYy8rcLHdorayXbsT3iQ7MhbnharKpE=; b=M3N9Gj1Ihv8I9YUfstwtzWIFX3+X2U9J5CpGZ6oP7Di3hrzt3WsVVJv1AOAErs7Ove CUu06Y8twnNwBNCHrSlB2nck7Vs5gxPbe0zltkHifMwKwABBUophuepqxMzpFUdWTCA3 Qap36HEHkzX9ZZ59g3CLLXZob5ZWjMinDx1ttADn2Ah8kn9kYVxYd6Lxygin2qWGA+MY MruND7adGncDE2d/mlXQ2mp/HQtqB/n1A3qAQ11K0HNW7hKknR+WGr1NyByh5uKO+I5l QtnBiarBhsYIBGx1XvhsYuZVbmKa+oCrmut3yi6UzUbQBfaIZEcBZGhDCEi1c+nXbBDa +uiQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; t=1689763901; s=strato-dkim-0003; d=tomerius.de; h=In-Reply-To:References:Message-ID:Subject:Cc:To:From:Date:Cc:Date: From:Subject:Sender; bh=lvLGZstJ8wKorYy8rcLHdorayXbsT3iQ7MhbnharKpE=; b=izeiG+UjQBLTpfzhdAuho9H+oPiIG8m14QCvDr/1SnrXC/4LZIUG7e8H9/IuiaHNyB l7nJ7yHBtDsAwrCpWADQ== Content-Disposition: inline In-Reply-To: <20230718213212.GE3842864@mit.edu> List-ID: Content-Type: text/plain; charset="us-ascii" To: Theodore Ts'o Cc: "Alan C. Assis" , =?iso-8859-1?Q?Bj=F8rn?= Forsman , linux-embedded@vger.kernel.org, Ext4 Developers List , dm-devel@redhat.com > In answer to Kai's original question, the setup that was described > should be fine --- assuming high quality hardware. I wonder how to judge that ... it's an eMMC supposedly complying to some JEDEC standard, so it *should* be ok. > ... if power is cut suddenly, the data used by the Flash > Translation Layer can be corrupted, in which case data written months > or years ago (not just recent data) could be lost. At least I haven't observed anything like that up to now. But on another aspect: how about the interaction between dm-integrity and ext4? Sure, they each have their own journal, and they're independent layers. Is there anything that could go wrong, say a block that can't be recovered in the dm-integrity layer, causing ext4 to run into trouble, e.g., an I/O error that prevents ext4 from mounting? I assume tne answer is "No", but can I be sure? Thx regards Kai