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<H2 CLASS="western"><FONT FACE="Tahoma, sans-serif"><FONT SIZE=4 STYLE="font-size: 15pt"><SPAN STYLE="font-style: normal">Daylight Saving Time </SPAN><SPAN STYLE="font-style: normal"><SPAN STYLE="font-weight: normal">(Windows)</SPAN></SPAN></FONT></FONT></H2>
<P STYLE="margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif">A
common problem synchronization software has to handle are +-1 hour
file time shifts after a Daylight Saving Time (DST) switch has
occurred. This can be observed for example when a FAT-formatted
volume is compared against an NTFS volume as is the case when synchronizing a local disk against a
USB memory stick. Files that previously appeared to be in sync are
now shown with an one hour modification time offset, although they
have not been modified by the user or the operating system.</FONT></P>
<P STYLE="margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif">The
reason for this behavior lies in the way NTFS and FAT drives
store file times: NTFS stores time in UTC format, while FAT uses
local time.</FONT></P>
<P STYLE="margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif">When
times of these two different formats are compared, one format
has to be converted into the other first. In either way Windows uses
the current DST status as well as the current time zone for
its calculations. Consequently the result of this comparison is
dependent from current system settings and in particular file times
that used to be the same can show up as different after a DST switch or when the time zone is changed.</FONT></P>
<P STYLE="margin-bottom: 0cm"><BR>
</P>
<P STYLE="margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif">For a
detailed discussion about this issue refer to:
<A HREF="http://www.codeproject.com/KB/datetime/dstbugs.aspx">http://www.codeproject.com/KB/datetime/dstbugs.aspx</A></FONT></P>
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</P>
<P STYLE="margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif"><B>Solution:</B></FONT></P>
<P STYLE="margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif">
FreeFileSync automatically handles this problem by adding the missing time information. Each file on a
FAT volume automatically gets additional meta data encoded in its
creation date that enables a correct file time calculation. This not
only solves all DST issues but also time shifts that occur due to
travel between different time zones.</FONT></P>
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<P ALIGN=LEFT STYLE="margin-left: 0.79cm; margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif"><B>Note</B></FONT></P>
<LI><P ALIGN=LEFT STYLE="margin-left: 0.79cm; margin-bottom: 0cm"><FONT FACE="Tahoma, sans-serif">In
order for FreeFileSync to start handling DST and timezone
differences, an initial full synchronization is required.
Subsequent syncs will then never show a time difference again for unchanged files.</FONT></P>
<LI><P ALIGN=LEFT STYLE="margin-left: 0.79cm; margin-bottom: 0cm; font-style: normal">
<FONT FACE="Tahoma, sans-serif">If a FAT volume is scanned the
first time by FreeFileSync this will take longer than usual since
additional meta data is written for each file.</FONT></P>
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