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Date: Tue, 3 Mar 2009 12:26:17 -0500
Message-ID: <87f94c370903030926m278f5ed3l70ca5faee28e57eb@mail.gmail.com>
Subject: Re: rsync hanging on Access MDB file
From: Greg Freemyer <greg DOT freemyer AT gmail DOT com>
To: cygwin AT cygwin DOT com
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On Tue, Mar 3, 2009 at 12:13 PM, Spiro Trikaliotis
> Hello Greg,
>
> * On Tue, Mar 03, 2009 at 10:20:52AM -0500 Greg Freemyer wrote:
>> On Tue, Mar 3, 2009 at 3:36 AM, Spiro Trikaliotis
>> <XXXXXXXXX AT spiro DOT trikaliotis DOT net> wrote:
>
> Please do not cite mail addresses!
>
>> > Thus, can you really rule out that noone else is accessing this file
>> > while rsync is taking place? My experience with Access is rather old
>> > (Access 1.1 and 2.0, some 15 years ago), but for these ancient versions,
>> > every time someone accesses this database, he opens the .mdb file
>> > himself in a shared manner. Thus, even if nothing is running on the
>> > server, there might be some remote user that is still accessing the DB.
> [...]
>> The above is exactly why VSS was created by Microsoft.
>
> Unfortunately, if you take a shadow copy of an open file, you might end
> with a correctly copied (or rsync'ed) file which is broken. You must be
> sure that noone is accessing the file at the moment you take the shadow
> copy.

I don't use Access, but in general good applications should support
being quiesced.  They do that by registering with the VSS service.
Then when a shadow copy is requested, vss first notifies all
registered apps to quiesce themselves.

Once all registered apps are quiesced, the shadow copy is created.

The whole purpose of the process is to ensure logically consistent
data is captured in the backup.

NTbackup from Microsoft is using vss to make its backups, so I would
be very surprised if Access is not registering itself and fitting into
Microsoft's master plan.

Greg
-- 
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