[nSLUG] rsync questions

Daniel Morrison draker at gmail.com
Tue Feb 22 11:06:53 AST 2011

Hello Mike,

An rsync server is also faster than using rsync over ssh, as you skip
the encryption step. But you should do this only if you trust your
local network.

rsync from an NFS mount to a local disk is less efficient than
connecting to a remote server using the rsync or rsync over ssh
protocols. However exactly HOW MUCH less efficient depends on your
options and the types of files involved.

The default for rsync is to skip transfers of entire files if the file
size and timestamp are the same. So this works fine when using rsync
from the NFS mount to local disk.

However if you turn on checksumming (-c) then rsync will need to
transfer every bit of data through the NFS mount in order to checksum
it before deciding it does not need to be transferred.

Since you are using NFS, you must trust your local network (right?) so
I would recommend seting up rsyncd.conf and not using ssh. In addition
to being the fastest method, you easily get the other advantages
outlined below by Dan.

I use rsync over ssh for small "one-off" transfers or anything private
going over the public Internet, but I have setup an rsync server
(running as root) for my regularly scheduled backups, and use plain
rsync for downloading free software (e.g. Slackware patches).


On 22 February 2011 09:33, Daniel MacKay <daniel at bonmot.ca> wrote:
>> I normally also do not use the rsync server, and prefer
>> to go over the default ssh connection, which may be more secure, tested,
>> and robust.  I use it even on a LAN.
> I *do* use the rsync server, because it (well, mine does) runs as root and can write files as root; so when I do a backup of files from one machine to another, they have correct owners, modification dates and permissions.
> As well as a fairly sophisticated username / password system (e.g. each username only has access to the things that you specify), the rsync server can be configured (per username) to only accept connections from particular hosts, and for even more fussiness you could put it behind tcpwrapper or iptables etc.
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