Timestamps

Particularly when you want to use some of the synchronization features, first make sure that WinSCP will be able to convert timestamps from local conventions to remote server conventions and vice versa.

Conversion

There are several factors that affect conversion and interpretation of the timestamps:

Factor Symptom
Daylight saving time (DST) Timestamps of some files are shifted by one hour. WinSCP requires Windows option Automatically adjust clock for Daylight Saving Time to be enabled.1)
Server timezone offset Timestamps of all files are shifted by the same time span. SCP and FTP protocols are affected.
Local file system is FAT File timestamp is always rounded to the next even second. This is a limitation of the legacy FAT filesystem. For this reason WinSCP ignores less than 2-seconds time difference with all its synchronization features. Although FAT is an old filesystem, it remains in common use today on flash based storage media and devices (such as USB flash drives, camera cards, phone internal storage, portable audio players etc). Standard ZIP archive files also use a similar timestamp system internally, so unzipped files will behave as if they have been copied from a FAT filesystem.
Timestamp precision Files changed shortly after previous synchronization are not synchronized. SCP and FTP protocols are affected.2)
Capability of updating remote file timestamp Some servers do not allow updating remote file timestamp at all. This severely restricts synchronization functionality. Some FTP servers and most WebDAV servers are affected.

Also note that for WinSCP to try to convert file timestamp at all, you need to have transfer option Preserve timestamp enabled.

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Windows vs. Unix

For certain reasons certain versions of Microsoft Windows (XP, 2003, Vista and 2008)3) shifts timestamps of ALL files by one hour once Daylight Saving Time starts and/or finishes4). For example, for file created on 2005-02-25 14:00, Windows applications (like Windows Explorer or WinSCP) will show modification time 2005-02-25 15:00, when DST is in effect. Unfortunately, to allow synchronization functions to work, WinSCP has to apply the same correction to timestamps of remote files as Windows apply to timestamps of local files. As the remote operating system, being typically Unix-style, usually does not perform the Windows NT-style correction, you will see by default different timestamps in directory listing of WinSCP, than you see in directory listing on the server (for example in ls listing). You can change this in session options, but that will render synchronization non-functional.

Synchronization

If you happen to have the same files locally and remotely with the different timestamps, you can update them without transferring the files again. Use function Synchronize in Synchronize timestamps mode.

Troubleshooting

1) The option is enabled by default and can be configured in Control Panel > Clock, Language and Region > Date and Time > Change time zone.
2) You can see in the remote file panel, with what precision does WinSCP know the remote file timestamp. So if panel shows e.g. dd/mm/yyyy hh:mm (minute precision), then if you change already synchronized local file within the same minute, WinSCP cannot recognize the change and won’t synchronize the file again.
3) Basically all NT-class versions of Windows until Windows Vista/2008. The timestamp shifting was removed since Windows 7/2008 R2.
 
  timestamp.txt · Last modified: by prikryl
 

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