Re: Rsync options –update and –append-verify

[Kevin Korb]

--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.  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.

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.
> 

-- 
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	Kevin Korb			Phone:    (407) 252-6853
	Systems Administrator		Internet:
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