rsync 3.1.1: --ignore-missing-args / --delete-missing args problem

Georgy Fedorov
Fri, 07 Apr 2017 12:58:08 -0000

Dear All,

We sometimes have to replicate large "live" filesystems with many (
sometimes millions, up to few hundred millions ) files on them. (
Copying actively used files is of course a bad idea, but it really helps
to keep the delta small, so one final transfer can later save the day. )

The problem, as one may guess, is that some files may disappear during
the process, so rsync finishes with an error code 23.
The good news is that since version 3.1.0 rsync has two options to
address this problem: --ignore-missing-args and --delete-missing-args .

The bad news, however, is that even with any of these, when the file
disappears, rsync handles the file transfer properly, but then tries to
set times or attributes on these files nevertheless. That fails with
errno 22 ( EINVAL ) and still leads to exit code 23, which is a bit of
an annoyance.

I am currently trying to come up with a patch to address this issue,
since I'd like to have exit code 0 for either of --ignore-missing-args
or --delete-missing-args, when the files are, well, missing.

Probably it is not the right way to address this problem, but in the
same vein as --ignore-missing-args are implemented, the patch can go as
follows:
https://gist.github.com/anonymous/96ba8bf10f864a93fd9203f75c43ffe9 .

Basically we need to do two changes:

(1) in options.c, make sure that the "missing_args" value is
transferred
when set ; and
(2) in rsync.c, in the "missing_args" case, replace FERROR_XFER with
something else, since apparently any log message with logcode
FERROR_XFER sets the flag 'got_xfer_error' in log.c, and that finally
leads to exit code RERR_PARTIAL (23), which is what we are trying to avoid.

I am currently testing this on fairly big datasets to see if there's
something missing, and will write more when I see how it goes ( as I
said, the data sets are fairly large ).

There shall be a better way to address that, but this is all I can do
with a very shallow acquaintance with rsync source code. Nevertheless,
it would be great if that could be fixed in the trunk one way or another )

Kind regards, George

--
George Fedorov
Senior Systems Specialist
Melbourne School of Engineering
The University of Melbourne, Victoria 3010, Australia
phone: *****
email: *****
http://www.eng.unimelb.edu.au/

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