File Timestamps

 

Timestamps are the date and time assigned to a file.  To make things more complex, there are two main types of timestamps :

 

 

When you copy a file it changes to timestamp of the "last accessed" field to that exact date & time. But it does not change the "Modified" timestamp since you have not modified it. Same thing happens if you open and read a file but do not change it.

Some utilities, such as "Showsize - Fined unused Files", and "Norton Utilities Speedisk", rely on accessing the date and time that files were last "accessed". This is not the same as the "Modified" date/time that you see in Windows Explorer. 

To see the "Last Accessed" timestamp, go to a DOS prompt and list the selected files using the DIR command with the /A/V/P switches. This command will work with Windows DOS boxes but not DOS 6.22 and before. 

NOTE: even though Windows Explorer will list a "Last Accessed" date if you right-click on a file and select "Properties" - it stupidly always lists Today's Date/Time because by right-clicking on the file, you have just "accessed it".



How the "Last Accessed" Timestamp can be Wrong

 

Windows and the file system is tasked to maintain the correct 'Last access date' for files.  But this information may not be correct for certain types of files and file systems!! You must understand that some situations might affect the access date of the files.

If you run a Virus Scan operation regularly on all the files, perhaps, every day. What happens is that a Virus Scan may mark each file as "used" on the date that you run the scan. More technically speaking, it updates the Last Access Date to the date when you run a Virus Scan. As a result, an important piece of information, that shows when a file was actually used last, is lost. Perhaps, some day, Virus Scan software would be smart enough to restore the original access date after a scan. Till then, you have to live with this problem.

As an example, I recently ran Showsize' "Find Unused Files" utility. I set it to show meall files in the c:\windows\system folder that had not been used for over 100 days. It came back with zero files. I looked in that folder using Explorer and there were plenty of files whose "Modified" timestamp was 1, 2 and even 3 years old. I know my Norton Antivirus does not automatically scan all my files so I found this to be curious. BUT - I'll bet it does scan all files in the system folder.

THE NORTON UTLITIES "Invalid Dates and Timestamps" PROBLEM

Norton Utilities has found files with Invalid Dates and Timestamps and failed to fix them. Explorer only shows you the Modified date - not the last accessed date, unless you right-click on a file and select "Properties" - but it always lists Today's Date/Time because by right-clicking on the file, you have just "accessed it". To see both the Modified date and Accessed date, go to a DOS prompt and list the selected files using the DIR command with the /A/V/P switches. 

When a computer's date is set to something other than the current date, many files end up with a Last Accessed Date that is in the future, or before the Modify Date or Create Date. These incorrect dates cause a variety of problems, depending on which files were changed.

The Fix - either go to options in Norton and disable the testing of the dates and timestamps, reinstall the program (if it is a newly installed program causing trouble), or copy the files to a new folder. delete the original ones, and recopy them back to the original folder - this will fix their dates (and timestamps).

Article:
http://service1.symantec.com/SUPPORT/sharedtech.nsf/docid/1998527114414