From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f174.google.com ([74.125.82.174]:42799 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753138AbbBSOau (ORCPT ); Thu, 19 Feb 2015 09:30:50 -0500 Received: by wesw62 with SMTP id w62so53109wes.9 for ; Thu, 19 Feb 2015 06:30:49 -0800 (PST) Message-ID: <54E5F38D.4070104@gmail.com> Date: Thu, 19 Feb 2015 16:30:37 +0200 From: Konstantinos Skarlatos MIME-Version: 1.0 To: "btr >> linux-btrfs@vger.kernel.org" CC: lennart Poettering Subject: Systemd 219 journald now sets the FS_NOCOW file flag for its journal files, possibly breaking RAID repairs. Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Systemd 219 now sets the special FS_NOCOW file flag for its journal files[1]. This unfortunately breaks the ability to repair the journal on RAID 1/5/6 btrfs volumes, should a bad sector happen to appear there. Is this something that can be configured for systemd? Is btrfs going to someday fix the fragmentation problem, making this option reduntant? [1] http://lists.freedesktop.org/archives/systemd-devel/2015-February/028447.html * journald now sets the special FS_NOCOW file flag for its journal files. This should improve performance on btrfs, by avoiding heavy fragmentation when journald's write-pattern is used on COW file systems. It degrades btrfs' data integrity guarantees for the files to the same levels as for ext3/ext4 however. This should be OK though as journald does its own data integrity checks and all its objects are checksummed on disk. Also, journald should handle btrfs disk full events a lot more gracefully now, by processing SIGBUS errors, and not relying on fallocate() anymore.