(Not retransferring files deleted from destination)

[Low, Alex]

Hi Matt,

Phew ! you were quick, and it's very much appreciated.


Ok.

We have three Solaris servers, and we have an Oracle database running on
each of them, 1 Primary (prod) and 
2 standbys (one 24 hours behind Prod & and the other 4 hours behind
Production).

The Arch logs are shipped from Prod Primary automatically, firstly, to
the 24-hour Standby as they are generated in Prod.  From there, the same
arch logs are copied to the 2nd server hosting the 2nd standby using
rsync.

On the 2nd standby server, the arch logs are deleted (for space
management)
once the 4-hour-behind-Prod standby database has been rolled forward.  
So, we have created ourselves a situation with arch logs where the 2nd
standby server Has LESS arch logs than the 1st standby.  

At present, rsync re-transfers those arch logs which have been removed
from
the 2nd standby.  This is undesirable because disk space is being
consumed again unnecessarily.  So, we are hoping that  rsync can be
programmed via soft switches that arch logs from the 1st standy host,
once transferred for the first time, will NOT be re-transferred as the
2nd standby has rolled forward the logs and they are no longer needed.

Hope you can suggest an rsync solution which will help overcome our
issue
As outlined above.

Thanks very much.

Cheers.

Alex.



-----Original Message-----
From: Matt McCutchen [mailto:matt at mattmccutchen.net] 
Sent: Monday, 22 June 2009 9:47 AM
To: Low, Alex
Cc: rsync at lists.samba.org
Subject: Re: (Not retransferring files deleted from destination)

On Mon, 2009-06-22 at 09:24 +0800, Low, Alex wrote:
> We do have a situation now where we need rsync to transfer the files
> once only from the source directory.  Please let me briefly explain
> 
> using a simple generic exmple:
> 
> 1. At t0, we transfer f0 location A to location B
> 
> 2. At t1, 10 new files are added to Location A
> 
> Therefore, rysnc faithfully transfers all 10 new files to location B
> 
> At location B, we now have f0 to f10.
> 
> 3. At t2, f0 to f3 are deleted from location B, and we don't ever want
> the deleted files to be copied again from location A
> 
> 4. At t3,  rysnc waits up, transfers files f0 and f10 again plus any
> new files that may have been added.
> 
> So, at location B, we end with the deleted files f0 to f3 again.
> 
> Can you please think of a way we can soft-switch rsync NOT to do step
> 4 above ?

As a stateless one-way mirroring tool, rsync doesn't support that
(unless you count --remove-source-files).  If you could provide some
more insight into your workflow, I might be able to come up with a
suitable alternative approach.

-- 
Matt


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