Future RSYNC enhancement/improvement suggestions

[Jason Haar]

On Mon, Apr 22, 2002 at 01:01:13PM -0400, David Bolen wrote:
> Unless you have quite large files, in which case there can be a
> lengthy period (particularly if the file is being accessed across a
> local network) while checksums are computed where there is no traffic
> at all.  For a while (when we had slow drives and a 10BaseT network)
> we could take 20-30 minutes for checksum computation on a 500-600MB
> database file with 4K blocks.  And our long distance dialup call was
> completely idle during that period.

...But then you should have a dialup timeout of 1 hour set?

Even firewalls default to around 1 hour (i.e. default Cisco CBAC tcp timeout
is 1 hour)

I think the problem is that you're morally upset that rsync spends so
much time sending no network traffic. Quite understandable ;-)

What about separating the tree into subtrees and rsyncing them? That means
you go from:

1> dialup connection started [quick]
2> rsync generates checksums (no network traffic) [slow]
3> rsync transmits files 

to:

1> dialup connection started [quick]
2> rsync generates subtree checksums (no network traffic) [quick]
3> rsync transmits files
4> rsync generates subtree checksums (no network traffic) [quick]
5> rsync transmits files
...etc

That would send a little bit more network traffic, but will it take
up less total dialup time? I don't know...

[guess it's time for a DJB saying: "don't speculate - evaluate!"]

-- 
Cheers

Jason Haar

Information Security Manager
Trimble Navigation Ltd.
Phone: +64 3 9635 377 Fax: +64 3 9635 417