Rsync options –update and –append-verify

[hancooper]

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, September 11, 2021 11:20 PM, Kevin Korb via rsync <rsync at lists.samba.org> wrote:

> --archive is all you really need. I actually wish --archive was the
> default because it is all most people need and with the exception of
> writing to a FAT filesystem it is almost always needed.
>
> --append is for very special cases and should only be used if you really
> know you need it and why. --append-verify only exists because people
> seem to think they need --append and get annoyed that it corrupts their
> files.
>
> --update is sometimes helpful however it interacts badly with --partial
> and --inplace.

That's right.  Can you elaborate how --update interacts badly with --partial
and --inplace?

> Since rsync doesn't set the timestamp of a file until it
> is finished then any file left incomplete by an aborted rsync will have
> the timestamp of the abort not the source file. Therefore it will be
> newer than the source file and unless the source is updated rsync
> --update will never complete the file.

Is there a solution to this problem and should we consider it a bug?
I am encountering this, and it's a real problem for me if files are
not completed.

> On 9/11/21 6:50 PM, hancooper via rsync wrote:
>
> > I am struggling to understand exactly what the rsync options --update and --append-verify do.
> > Doing info rsync gives
> > -u, --update
> > This forces rsync to skip any files which exist on the destina‐
> > tion and have a modified time that is newer than the source
> > file. (If an existing destination file has a modification time
> > equal to the source file’s, it will be updated if the sizes are
> > different.)
> > --append-verify
> > This works just like the --append option, but the existing data
> > on the receiving side is included in the full-file checksum
> > verification step, which will cause a file to be resent if the
> > final verification step fails (rsync uses a normal, non-append‐
> > ing --inplace transfer for the resend).
> > I am using rsync to transfer directories recursively. There are times where I have to stop the rsync transfer, and resume the transfer a few hours or days later, without affecting the already transferred files at destination.
> > I also got some files that return errors by rsync, such as
> > rsync: read errors mapping "/media/hc1/a1-chaos/amvib/IACL-2017-07-19T00:00:00-2017-07-19T23:59:59.mseed": Input/output error (5)
> > I would like to retry the transfer of these files, at a later time too, without affecting the files that had been transferred successfully.
>