[ale] rsync comparisons

[Pat Regan]

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On 04/02/10 00:53, Robert Coggins wrote:
> Well, I have the sync running within a respectable amount of time.  The
> first way I was running the rsync was taking over an hour:
> 
> rsync -a --delete --exclude=afolder /path/a /path/b
> where /path/a is an nfs mount on a SAN and /path/b is an nfs mount on a
> server

In this case rsync has to transfer entire files around since they are
both on the local file system, at least as far as rsync is concerned.

> But now with the following I am down to about 5 minutes:
> 
> rsync -a -e ssh --delete --exclude=afolder /path/a server:/real/path/b
> 

In this case an rsync instance is running on each machine.  The rsync
instances compute checksums and decide which individual blocks need to
be transfered.  This means you get to take advantage of the fast disks
on each end point and only use the slow network to transfer the deltas.

Pat
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