mirror of https://github.com/mkerrisk/man-pages
mount.2: Enhancements to MS_LAZYTIME description
Cowritten-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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man2/mount.2
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man2/mount.2
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@ -173,9 +173,25 @@ an undeleted inode is evicted from memory; or
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more than 24 hours have passed since the inode was written to disk.
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more than 24 hours have passed since the inode was written to disk.
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.RE
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.RE
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.IP
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.IP
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This mount option significantly reduces writes to the inode table
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This mount significantly reduces writes
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for some workloads
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needed to update the inode's timestamps, especially mtime and atime.
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(e.g., when performing frequent random writes to preallocated files).
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However, in the event of a system crash, the atime and mtime fields
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on disk might be out of date by up to 24 hours.
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Examples of workloads where this option could be of significant benefit
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include frequent random writes to preallocated files,
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as well as cases where the
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.B MS_STRICTATIME
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mount option is also enabled.
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(The advantage of
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.I "(MS_STRICTATIME\ | MS_LAZYTIME)"
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is that
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.BR stat (2)
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will return the correctly updated atime, but the atime updates
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will be flushed to disk only when (1) the inode needs to be
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updated for filesystem / data consistency reasons or (2) the
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inode is pushed out of memory, or (3) the filesystem is
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unmounted.)
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.TP
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.TP
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.B MS_MANDLOCK
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.B MS_MANDLOCK
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Permit mandatory locking on files in this filesystem.
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Permit mandatory locking on files in this filesystem.
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