rsync - Sep 2011 - rsync (or rsync-like tool) provides local metadata cache ?

Let's say I have a slow, or high latency (or both) link between two hosts,
and transferring data is expensive.

Is it possible with rsync (or any other tool like rsync) to maintain a local
metadata cache, such that I can rsync without transferring data to and from the
hosts about what files are already in place ?

That is, I already "know" what is out there and don't need to
check anything - I can just use the state information on the sending end to send
only the data required, and don't need to traverse the remote filesystem for
sizes/datestamps/hashes/etc.

Does this exist ?

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You want something real time like lsyncd.

On 09/29/11 19:57, Jason Usher wrote:
> Let's say I have a slow, or high latency (or both) link between two
hosts, and transferring data is expensive.
> 
> Is it possible with rsync (or any other tool like rsync) to maintain a
local metadata cache, such that I can rsync without transferring data to and
from the hosts about what files are already in place ?
> 
> That is, I already "know" what is out there and don't need to
check anything - I can just use the state information on the sending end to send
only the data required, and don't need to traverse the remote filesystem for
sizes/datestamps/hashes/etc.
> 
> Does this exist ?
- -- 
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	Kevin Korb			Phone:    (407) 252-6853
	Systems Administrator		Internet:
	FutureQuest, Inc.		Kevin at FutureQuest.net  (work)
	Orlando, Florida		kmk at sanitarium.net (personal)
	Web page:			http://www.sanitarium.net/
	PGP public key available on web site.
~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~
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On 30/09/2011 00:57, Jason Usher wrote:
> Let's say I have a slow, or high latency (or both) link between two
> hosts, and transferring data is expensive.
> 
> Is it possible with rsync (or any other tool like rsync) to maintain
> a local metadata cache, such that I can rsync without transferring
> data to and from the hosts about what files are already in place ?
> 
> That is, I already "know" what is out there and don't need to
check
> anything - I can just use the state information on the sending end to
> send only the data required, and don't need to traverse the remote
> filesystem for sizes/datestamps/hashes/etc.
> 
> Does this exist ?
Check out the checksum database patches. Maybe these could help in your
case...