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Number   :  18
Date     :  2001-05-13
Author   :  Kan Yabumoto
Subject  :  Re: XXCOPY in a Netware Mapped drive
Size(KB) :  1



Max,

It's not XXCOPY, XCOPY or COPY which handles the timestamp. The
file system (the software component which is responsible for the NTFS,
FAT (I did not distinguish FAT12, FAT16, or FAT32 because they
all behave the same way with regard to the timestamp).

Let me repeat what I said. When you copy a file which was created
on a NTFS volume into a FAT volume using any of the file-copy tools,
the file time will be changed unless the file time happens to be
already aligned to the exact two-second granularity. When you
compare the file time (I don't care which tool you use to compare the
file time) between the one in the NTFS and the one in the FAT volume,
you will see the difference. Since XXCOPY's incremental backup scheme
(the /CLONE or /BI switch) considers the two are different when either
the file size or file time is different, the file will undergo
backup (uncecessary) copy. If you use the archive-bit based incremental
backup (using the /M switch), then the operation does not look at
the timestamp (but rather, the archive bit), the file would be
skipped even if the two file times between the source and the backup
directories are slightly different due to the timestamp truncation
which took place in the first backup operation.

In other words, the difference in time value precision (granularity)
maintained by the various file systems cause the timestamp
value to change when a file is copied from the higher-precision
file system (NTFS) to the less-precision (FAT) file system. This
is nothing to do with XXCOPY.

Kan Yabumoto


=======================================================================
At 2001-05-13 00:40, max08122000@y... wrote:

>What I don't understand is that why the simple NT's xcopy or copy
>works or preserves the date and time in this case.?
>
>I'll get a FAT volume up in the w2k svr (how about FAT32?) to give it
>another try and also the v2557 version. Cheers.
>
>Regards,
>MAX



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