[TriLUG] copying files

[Joseph Mack NA3T]

On Fri, 22 Jun 2012, Jeff Schornick wrote:

>>> just doing an fstat() (or similar) on the other end?
>>
>> following Alexy's comment, I see that several RTT's are 
>> involved. However I'm still not transferring cdimage.iso 
>> just the timestamps etc
>
> Right, but we're talking about 1000s of files.  So your 
> overhead to "collect the timestamps" is many orders of 
> magnitude slower than using rsync in the more traditional 
> sense.  Such that if you latency is high enough, it could 
> easily eclipse your overall sync time.
>
> Rsync is not optimized to be run against a filesystem that 
> appears to be local (nfs, sshfs), but one which incurs 
> latency on each read associated with a remote machine.

I see.

> If I'm reading you right, it appears you're still mounting 
> some sort of network filesystem from "far away".  Don't do 
> that if you plan on using rsync to sync many files.  Let 
> it do what it does best, where it calculates each of its 
> file lists on the respective machines.

OK. got it and I missed this too. I see that this is a 
logical extension of Alexy's point. In that case I've been 
barking up the wrong tree, comparing cp with rsync, both to 
filesystems that appear to be local. I should be comparing 
cp to a filesystem that appears to be local on one hand 
against rsync running local talking to rsync running on a 
remote machine.

groan

Thanks
Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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