Hello there,
Not sure if anyone else saw this problem but this comes up a lot with my computers and backup drives like USB thumb drives and just about any other kind of drive.
The problem is that Windows stores files on one drive with a time stamp that is either one or two hours behind the other drive. This is not only annoying, it means that a quick sanity check of the files can no longer be done by just checking the file size and date and time stamp. I'll give an example.
The entries will be in this order:
FILENAME, SIZE, DATE, TIME (where SIZE is the number of bytes of the file)
Drive1:
MyFile1.jpg, 10340 bytes, 2022/03/12 10:41:03
Drive2:
MyFile1.jpg, 10340 bytes, 2022/03/12 08:41:03
Now normally these two files would be considered to be different because they were modified at two different times. However, the time for the second file is exactly 2 hours different (sometimes it will be just 1 hour different) and that is strange right off. The problem is, these two files are exactly the same, byte for byte.
Now other files that are off by 2 hours (or 1 hour) may be really different, so it is possible that those two are different.
See the problem? You cant tell if they are different or not, to be sure.
In most cases the different files will have times that differ by something other than just 1 or 2 hours, but there is a chance that they could really be different.
I think there is a 1 in 3600 chance of them being different if they have times that are off by exactly 1 or 2 hours (no difference in minutes or seconds). That's not really very good odds when you have thousands, hundreds of thousands, or millions of files to check.
Of course i could do a byte by byte file comparison on each and every file, but that of course takes more time. The size and date and time check is fast.
Also of course if the sizes are different than the files are truly different so the problem is only with the date and time.
Also note that it is not as simple as adding or subtracting 1 or 2 hours from one of the file times, because it could mean that it affects the date too. For example,
if date time A is 2022/03/24 23:33:54 and date time B is 2022/03/25 01:33:54 then both the time and date have to be considered, and that means we have to know the number of days in that month because it could also overrun the month itself if it is near the beginning or end of the month, and then also the year if near the end or beginning of the year. That would be more rare, but still a possibility.
Any thoughts on this?
Not sure if anyone else saw this problem but this comes up a lot with my computers and backup drives like USB thumb drives and just about any other kind of drive.
The problem is that Windows stores files on one drive with a time stamp that is either one or two hours behind the other drive. This is not only annoying, it means that a quick sanity check of the files can no longer be done by just checking the file size and date and time stamp. I'll give an example.
The entries will be in this order:
FILENAME, SIZE, DATE, TIME (where SIZE is the number of bytes of the file)
Drive1:
MyFile1.jpg, 10340 bytes, 2022/03/12 10:41:03
Drive2:
MyFile1.jpg, 10340 bytes, 2022/03/12 08:41:03
Now normally these two files would be considered to be different because they were modified at two different times. However, the time for the second file is exactly 2 hours different (sometimes it will be just 1 hour different) and that is strange right off. The problem is, these two files are exactly the same, byte for byte.
Now other files that are off by 2 hours (or 1 hour) may be really different, so it is possible that those two are different.
See the problem? You cant tell if they are different or not, to be sure.
In most cases the different files will have times that differ by something other than just 1 or 2 hours, but there is a chance that they could really be different.
I think there is a 1 in 3600 chance of them being different if they have times that are off by exactly 1 or 2 hours (no difference in minutes or seconds). That's not really very good odds when you have thousands, hundreds of thousands, or millions of files to check.
Of course i could do a byte by byte file comparison on each and every file, but that of course takes more time. The size and date and time check is fast.
Also of course if the sizes are different than the files are truly different so the problem is only with the date and time.
Also note that it is not as simple as adding or subtracting 1 or 2 hours from one of the file times, because it could mean that it affects the date too. For example,
if date time A is 2022/03/24 23:33:54 and date time B is 2022/03/25 01:33:54 then both the time and date have to be considered, and that means we have to know the number of days in that month because it could also overrun the month itself if it is near the beginning or end of the month, and then also the year if near the end or beginning of the year. That would be more rare, but still a possibility.
Any thoughts on this?