rsync - Dec 2009 - DO NOT REPLY [Bug 6965] New: truncated files and exit code 23

https://bugzilla.samba.org/show_bug.cgi?id=6965

           Summary: truncated files and exit code 23
           Product: rsync
           Version: 3.0.4
          Platform: x86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: martin.pihlak at gmail.com
         QAContact: rsync-qa at samba.org


While backing up an active PostgreSQL database, I occasionally get exit code 23
from rsync, accompanied by a error messages:

rsync: read errors mapping
"/data/postgresql/8.3/main/base/144458723/1009564226":
No data available (61)
rsync error: some files could not be transferred (code 23) at main.c(1058)
[sender=3.0.3]

As indicated by http://lists.samba.org/archive/rsync/2009-November/024133.html
this is caused by the file being truncated while being read by rsync. On an
active database this is actually a normal condition, as files are created,
deleted and truncated all the time.

Unfortunately the code 23 cannot just be ignored, as it also may indicate that
there was an actual "real" IO error during the backup. And without
reading
rsync output there is no way to tell.

So the proposal is to avoid generating ENODATA for truncated files and treat
them similarly to vanished files.


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https://bugzilla.samba.org/show_bug.cgi?id=6965


matt at mattmccutchen.net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|truncated files and exit    |Avoid code 23 when source
                   |code 23                     |file is concurrently
                   |                            |truncated




------- Comment #1 from matt at mattmccutchen.net  2009-12-14 01:42 CST -------
Indeed.  This is probably one of many kinds of concurrent modification to the
source that rsync handles ungracefully.

In general, when different system calls return inconsistent results, that could
indicate either a concurrent modification or filesystem misbehavior.  The
downside to always assuming concurrent modification is that we miss the
opportunity to report filesystem misbehavior if it happens.  One example is the
Cygwin "file has vanished" error with foreign characters in filenames
(
http://lists.samba.org/archive/rsync/2008-January/019696.html ).


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