do I always have to use either --checksum or --times ?

[Robin Lee Powell]

--checksum is only slower than re-copying if your network connection
between the hosts is similar in speed (or faster than) each host's
local disk access.

If local disk access is 10x your network link, it is definitely not
slower than re-copying.

Having said that, it really is *very* slow, and before you use it
you should have a clear situation in mind that makes it plausible that
two files could have the same size and last mod time and still not
have the same data.

Or, alternately, be in a situation where a bit flip would be
catastrophic.  Such situations are not common.

On Thu, Jul 14, 2022 at 04:26:48AM -0400, Kevin Korb via rsync wrote:
> You should almost never use --checksum.  It is slower than just re-copying
> everything.  You should almost always use --times (or --archive which
> includes --times).  Without this rsync is almost as dumb as cp.  Also, ssh
> has been the default --ssh for a long time.
> 
> On 7/14/22 04:22, Fourhundred Thecat via rsync wrote:
> > Hello,
> > 
> > I want to sync local folder to remote server. When I run follwing
> > command repeatedly, it always transfers everything each time again and
> > again:
> > 
> >    rsync --rsh='ssh' foo/ server:/foo/
> > 
> > does it mean I have to always use either --checksum or --times, to
> > prevent repeated transfer of files that have not changed ?
> > 
> > thank you,
> > 
> 
> -- 
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