Mapped Drive

devzero at devzero at
Sun Sep 30 08:46:04 GMT 2007

for now there is no caching - anyway - how should checksums be cached?
if mtime/size is no reliable method for detecting file changes and checksum is the only method - to detect if you need to update the cache you need to ... checksum .... and thus a checksum cache is quite nonsense, imho.

> I suppose it could be cached at either storage location.
if you use rsync on a mapped drive, you have no "local" and "remote" storage location from an rsync`s point of view, because rsync isn`t being executed on the remote node. so if rsync calculates a checksum it`s always transferring the whole file via mapped drive.


> -----Ursprüngliche Nachricht-----
> Von: "Stephen Zemlicka" <stevezemlicka at>
> Gesendet: 30.09.07 07:30:04
> An: "'Matt McCutchen'" <hashproduct+rsync at>
> CC: rsync at
> Betreff: RE: Mapped Drive

> The problem is some files don't change in size.  So I was hoping that the
> checksums could be cached.  Perhaps I'm mistaken but I thought the checksum
> determined what actual blocks were transferred.  I suppose it could be
> cached at either storage location.
> _____________________________
> Stephen Zemlicka
> Integrated Computer Technologies
> PH. 608-558-5926
> E-Mail stevezemlicka at 
> -----Original Message-----
> From: hashproduct at [mailto:hashproduct at] On Behalf Of Matt
> McCutchen
> Sent: Saturday, September 29, 2007 5:03 PM
> To: Stephen Zemlicka
> Cc: rsync at
> Subject: Re: Mapped Drive
> On 9/28/07, Stephen Zemlicka <stevezemlicka at> wrote:
> > Is there a way to have rsync cache the checksums for something like this
> and
> > would that help?
> I'm not sure exactly what you mean.  You said you were using the -c
> (--checksum) option, which makes rsync decide whether to update each
> destination file by reading the file in full and comparing its MD4/MD5
> checksum with that of the source file.  Do you mean you want rsync to
> cache the checksums of the destination files?  On which machine would
> the cache be?
> Anyway, if the issue is that you don't want rsync spending the
> bandwidth to read the destination files for the --checksum check, just
> remove -c and rsync will use the default size-and-mtime quick check.
> Matt
> -- 
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