From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 93D207CA4 for ; Tue, 24 May 2016 07:58:59 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay1.corp.sgi.com (Postfix) with ESMTP id 59DAA8F804B for ; Tue, 24 May 2016 05:58:56 -0700 (PDT) Received: from mr003msb.fastweb.it (mr003msb.fastweb.it [85.18.95.87]) by cuda.sgi.com with ESMTP id qCFBUpkiR49VtEYq for ; Tue, 24 May 2016 05:58:53 -0700 (PDT) Received: from ceres.assyoma.it (93.63.55.57) by mr003msb.fastweb.it (8.5.140.04) id 572A172301273F91 for xfs@oss.sgi.com; Tue, 24 May 2016 14:58:52 +0200 Subject: LVM snapshot and log record CRC mismatch MIME-Version: 1.0 Date: Tue, 24 May 2016 14:58:51 +0200 From: Gionatan Danti Message-ID: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com Cc: g.danti@assyoma.it Hi list, I have a question about LVM snapshot and XFS. Some preliminary information: CentOS Linux release 7.0.1406 (Core), with kernel version 3.10.0-123.20.1.el7.x86_64 Basically, each time I mount a LVM snapshot (with the "nouuid" option), I have the following dmesg entries: [824501.391058] XFS (dm-7): Mounting Filesystem [824502.085459] XFS (dm-7): Starting recovery (logdev: internal) [824502.120435] XFS (dm-7): log record CRC mismatch: found 0x324293f8, expected 0x43a1b3b5. [824502.121035] ffffc90018271000: 00 00 00 10 00 00 00 00 69 01 00 00 6d a0 9d a7 ........i...m... [824502.121649] ffffc90018271010: 00 00 00 10 69 00 00 00 4e 41 52 54 2a 00 00 00 ....i...NART*... [824502.122403] XFS (dm-7): log record CRC mismatch: found 0x873f6b2, expected 0x49045c16. [824502.122952] ffffc90018271000: 00 00 00 10 00 00 00 08 aa 20 00 00 6e 55 00 00 ......... ..nU.. [824502.123508] ffffc90018271010: 00 00 00 00 69 00 00 00 4e 41 52 54 2a 00 00 00 ....i...NART*... [824502.124239] XFS (dm-7): log record CRC mismatch: found 0x2f6e47af, expected 0x7efb222. [824502.124792] ffffc90018271000: 00 00 00 10 00 00 00 00 69 01 00 00 a7 66 d7 2e ........i....f.. [824502.125359] ffffc90018271010: 00 00 00 10 69 00 00 00 4e 41 52 54 2a 00 00 00 ....i...NART*... [824502.126173] XFS (dm-7): log record CRC mismatch: found 0x324293f8, expected 0x43a1b3b5. [824502.126751] ffffc900182b2000: 00 00 00 10 00 00 00 00 69 01 00 00 6d a0 9d a7 ........i...m... [824502.127332] ffffc900182b2010: 00 00 00 10 69 00 00 00 4e 41 52 54 2a 00 00 00 ....i...NART*... [824502.153510] XFS (dm-7): log record CRC mismatch: found 0x873f6b2, expected 0x49045c16. [824502.154158] ffffc900182b2000: 00 00 00 10 00 00 00 08 aa 20 00 00 6e 55 00 00 ......... ..nU.. [824502.154818] ffffc900182b2010: 00 00 00 00 69 00 00 00 4e 41 52 54 2a 00 00 00 ....i...NART*... [824502.155654] XFS (dm-7): log record CRC mismatch: found 0x2f6e47af, expected 0x7efb222. [824502.156258] ffffc900182b2000: 00 00 00 10 00 00 00 00 69 01 00 00 a7 66 d7 2e ........i....f.. [824502.156869] ffffc900182b2010: 00 00 00 10 69 00 00 00 4e 41 52 54 2a 00 00 00 ....i...NART*... [824502.906702] XFS (dm-7): Ending recovery (logdev: internal) [824502.906714] SELinux: initialized (dev dm-7, type xfs), uses xattr From my understanding, this should be more or less the expected behavior: the snapshot is a "crash consistent" backup point, and mounting the snapshotted filesystem can led to mismatched CRC. Anyway, I can read from the snapshot without problems. However, issuing a xfs_info on the original volume shows that crc options is 0 (crc=0), so I am somewhat puzzled about the warning above. Moreover, on a more recent CentOS 7.2 server (kernel version 3.10.0-327.13.1.el7.x86_64), I can not reproduce this warning. So I ask: 1) it really is the expected behavior, or should I be worried by the dmesg entries? 2) this is kernel-related, should I update the kernel to newer version? Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs