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64 lines
2.6 KiB
64 lines
2.6 KiB
From 3740b7a6d246a5860c8f1d96504bbf00692447e0 Mon Sep 17 00:00:00 2001 |
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From: Goffredo Baroncelli <kreijack@inwind.it> |
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Date: Sun, 12 Apr 2015 20:30:28 +0200 |
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Subject: [PATCH] tmpfiles: Add +C attrib to the journal files directories |
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Add the +C file attribute (NOCOW) to the journal directories, so that |
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the flag is inherited automatically for new journal files created in |
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them. The journal write pattern is problematic on btrfs file systems as |
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it results in badly fragmented files when copy-on-write (COW) is used: |
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the performances decreases substantially over time. |
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To avoid this issue, this tmpfile.d snippet sets the NOCOW attribute to |
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the journal files directories, so newly created journal files inherit |
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the NCOOW attribute that disables copy-on-write. |
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Be aware that the NOCOW file attribute also disables btrfs checksumming |
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for these files, and thus prevents btrfs from rebuilding corrupted files |
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on a RAID filesystem. |
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In a single disk filesystems (or filesystems without redundancy) it is |
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safe to use the NOCOW flags without drawbacks, since the journal files |
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contain their own checksumming. |
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(cherry picked from commit 3a92e4ba470611ceec6693640b05eb248d62e32d) |
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Related: #1299714 |
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--- |
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tmpfiles.d/journal-nocow.conf | 27 +++++++++++++++++++++++++++ |
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1 file changed, 27 insertions(+) |
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create mode 100644 tmpfiles.d/journal-nocow.conf |
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diff --git a/tmpfiles.d/journal-nocow.conf b/tmpfiles.d/journal-nocow.conf |
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new file mode 100644 |
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index 0000000000..e7938c8911 |
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--- /dev/null |
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+++ b/tmpfiles.d/journal-nocow.conf |
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@@ -0,0 +1,27 @@ |
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+# This file is part of systemd. |
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+# |
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+# systemd is free software; you can redistribute it and/or modify it |
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+# under the terms of the GNU Lesser General Public License as published by |
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+# the Free Software Foundation; either version 2.1 of the License, or |
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+# (at your option) any later version. |
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+ |
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+# See tmpfiles.d(5) for details |
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+ |
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+# Set the NOCOW attribute for directories of journal files. This flag |
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+# is inheredited by their new files and sub-directories. Matters only |
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+# for btrfs filesystems. |
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+# |
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+# WARNING: Enabling the NOCOW attribute improves journal performance |
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+# substantially, but also disables the btrfs checksum logic. In |
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+# btrfs RAID filesystems the checksums are needed for rebuilding |
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+# corrupted files. Without checksums such rebuilds are not |
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+# possible. |
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+# |
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+# In a single-disk filesystem (or a filesystem without redundancy) |
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+# enabling the NOCOW attribute for journal files is safe, because |
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+# they have their own checksums and a rebuilding wouldn't be possible |
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+# in any case. |
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+ |
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+h /var/log/journal - - - - +C |
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+h /var/log/journal/%m - - - - +C |
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+h /var/log/journal/remote - - - - +C
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