Re: Copy slower than rsync Re: Bugs and features

[Nate Campi]

On Fri, Nov 08, 2002 at 02:44:55PM +0100, Adrian Phillips wrote:
> >>>>> "Mark" == Mark Burgess <mark@daneel.iu.hio.no> writes:
> 
>     Mark> * cfengine spreads things out over time (low CPU, slower
>     Mark> total time) rsync (high CPU, short total time). Thus with
>     Mark> multiple connections one would expect cfengine to
>     Mark> survive/scale longer than rsync.
> 
> Well, even a 1+GB partition only takes a few seconds on a fast,
> lightly loaded server with rsync even using ssh. Obviously when there
> are lots of differences then rsync is going to chew memory.

You have to mean a 1+GB partition with no changes. No disk subsystem
you're likely to be running will shove that kind of data out the network
card, even if you have a NIC and network layer that can handle it.

>     Mark> * rsync trusts everything and caches like mad to go fast.
> 
> This is rsync using ssh so there is a reasonably level of security
> involved, unlike rsyncs own server.

Unless you mean ssh using public key or kerberos or S/Key auth then this
is not security. Even then, you have encryption and good authentication,
which is mostly one way.

rsync's server could be made "secure" with IPSec and packet filtering,
so that you *know* the host it's originating from and filtering out all
others. You can't just say "rsync's server is insecure and rsync over
ssh is secure", because it leaves out too much.

> Anyway, currently I'm switching all my large copies over to
> shellcommand rsyncs to avoid this because I prefer to have cfagent
> running for as short a time as possible. Other people may have other
> preferences.

I also prefer to dist files using the same methods from all processes.
What I mean is that I don't use rdist from cron and rsync from the
command line to dist a group of files. rdist may not realize a file is
the same because timestamps differ, and needlessly transfer a large
file. If I use rsync for all file distribution, I can manually push
files in a pinch and know the results should be consistent with the
results of the automated pushes. Does that make sense? Using rsync for
all your file distribution should give you good predictable results.
-- 
Nate Campi   http://www.campin.net 

"Men are from Mars. Women are from Venus. Computers are from hell."

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