[CentOS] unison versus rsync

Thu Jan 14 18:27:14 UTC 2010
Bill Campbell <centos at celestial.com>

On Thu, Jan 14, 2010, Joseph L. Casale wrote:
>>I didn't think unison was maintained any more - and I wouldn't expect 
>>anything to beat rsync with the -z option on a slow link.  I'd just use 
>>the -P option and restart it when/if it fails.  It wouldn't hurt to do 
>>subsets first since they will be quickly skipped when you repeat from 
>>the root.  If you have a huge number of files it might be worth finding 
>>a way to update rsync to a 3.x version which will not need to xfer the 
>>entire directory listing before starting.
>Looks like rf has 3.0.7, thanks for that tip. Frankly, I abhor the thought
>of even using rsync for this, it's over a vpn so there is absolutely no need
>for encryption but I don't know another tool that can transfer diffs only?

If you use rsync modules, the transfer can be done without encryption, and
you restrict access to directories and specific IPs and CIDR blocks.

We use this extensively to allow remote clients to update things like DNS
files which go to client-specific directories, and are restricted to the IP
address(es) of the client's system(s).

Another feature of rsync modules that can be useful is that each module can
specify a user and group thus one can rsync user directories between
systems where the user names are the same but uid and gid may differ.

Rsync does not use ssh when doing module transfers so if the data is
sensitive, I do the transfers through OpenVPN tunnels.  This also
eliminates the problems of ssh authentication between trusted systems.

Given the ability of rsync modules to restrict access by IP address, I have
never bothered with additional authentication for this type of transfer.

INTERNET:   bill at celestial.com  Bill Campbell; Celestial Software LLC
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