37 lines
1.4 KiB
Plaintext
37 lines
1.4 KiB
Plaintext
<!-- doc/src/sgml/syncfs.sgml -->
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<appendix id="syncfs">
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<title><function>syncfs()</function> Caveats</title>
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<indexterm zone="syncfs">
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<primary>syncfs</primary>
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</indexterm>
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<para>
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On Linux <function>syncfs()</function> may be specified for some
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configuration parameters (e.g.,
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<xref linkend="guc-recovery-init-sync-method"/>), server applications (e.g.,
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<application>pg_upgrade</application>), and client applications (e.g.,
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<application>pg_basebackup</application>) that involve synchronizing many
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files to disk. <function>syncfs()</function> is advantageous in many cases,
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but there are some trade-offs to keep in mind.
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</para>
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<para>
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Since <function>syncfs()</function> instructs the operating system to
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synchronize a whole file system, it typically requires many fewer system
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calls than using <function>fsync()</function> to synchronize each file one by
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one. Therefore, using <function>syncfs()</function> may be a lot faster than
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using <function>fsync()</function>. However, it may be slower if a file
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system is shared by other applications that modify a lot of files, since
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those files will also be written to disk.
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</para>
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<para>
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Furthermore, on versions of Linux before 5.8, I/O errors encountered while
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writing data to disk may not be reported to the calling program, and relevant
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error messages may appear only in kernel logs.
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</para>
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</appendix>
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