From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mgwym04.jp.fujitsu.com ([211.128.242.43]:29663 "EHLO mgwym04.jp.fujitsu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751740AbdATJsA (ORCPT ); Fri, 20 Jan 2017 04:48:00 -0500 Date: Fri, 20 Jan 2017 18:24:48 +0900 From: Yasunori Goto To: Vishal Verma Subject: Re: [LSF/MM TOPIC] Badblocks checking/representation in filesystems Cc: Lu Zhang , Andreas Dilger , Slava Dubeyko , "Darrick J. Wong" , "linux-nvdimm@lists.01.org" , "linux-block@vger.kernel.org" , Linux FS Devel , Viacheslav Dubeyko , Andiry Xu , "lsf-pc@lists.linux-foundation.org" In-Reply-To: <20170120004633.GA14128@omniknight.lm.intel.com> References: <20170120004633.GA14128@omniknight.lm.intel.com> Message-Id: <20170120182435.0E12.E1E9C6FF@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hello, Virshal-san. First of all, your discussion is quite interesting for me. Thanks. > > > > If DUE does happen and is flagged to the file system via MCE (somehow...), > > and the fs finds that the error corrupts its allocated data page, or > > metadata, now if the fs wants to recover its data the intuition is that > > there needs to be a stronger error correction mechanism to correct the > > hardware-uncorrectable errors. So knowing the hardware ECC baseline is > > helpful for the file system to understand how severe are the faults in > > badblocks, and develop its recovery methods. > > Like mentioned before, this discussion is more about presentation of > errors in a known consumable format, rather than recovering from errors. > While recovering from errors is interesting, we already have layers > like RAID for that, and they are as applicable to NVDIMM backed storage > as they have been for disk/SSD based storage. I have one question here. Certainly, user can use LVM mirroring for storage mode of NVDIMM. However, NVDIMM has DAX mode. Can user use LVM mirroring for NVDIMM DAX mode? I could not find any information that LVM support DAX.... In addition, current specs of NVDIMM (*) only define interleave feature of NVDIMMs. They does not mention about mirroring feature. So, I don't understand how to use mirroring for DAX. (*) "NVDIMM Namespace Specification" , "NVDIMM Block Window Driver Writer’s Guide", and "ACPI 6.1" Regards, --- Yasunori Goto