Determining When To Sync (Transfer) A File
Files.com only uses filename and size to determine whether a file needs to be synced. It does not currently use information such as modified date or checksum for this purpose.
Due to the wide variety of remote server types supported, we've designed a methodology that works the most consistently across all remote server types.
Checking For Updated File
Our syncs with object storage remote servers of type AWS S3, Azure Blob, or Google Cloud Storage provide an extra file update check.
The sync will check to see if a file has changed, or been updated, since the time that the sync was started. If the file was changed, or updated, then it will be skipped from this sync.
This is to prevent the file from being transferred while it might be in a state of being actively updated and prevents partial files from being delivered to the destination.
Skipped files will be processed again in subsequent syncs.
Known Limitations
Our sync strategy works for over 98% of the use cases we've encountered at Files.com. There are a few cases where the use of Remote Server Sync does not work well.
We are working on additional functionality to allow sync to still work intelligently in these use cases.
Syncing Files to Microsoft SharePoint
Microsoft SharePoint will parse files in order to index and promote them within the SharePoint user interface. Files uploaded to a Document Library will be modified by SharePoint to include extra column and value metadata. The file size will increase and its modification time will be updated, causing the Sync to become unable to determine if the synched file matches the original.
Open Files and 3rd Party File Locks
Open files and 3rd party file locks on remote servers can result in invalid or partial data being synced, or prevent files from being synced.
3play's FTP Server
3play's FTP server has been found to report sizes incorrectly. Sync uses file size to determine whether a file should be transferred so unexpected outcomes will be observed.
In the meantime, we recommend that you disable Sync and instead use a Remote Server Mount in conjunction with a Copy File or Move File Automation in either of these cases.
We would be interested to learn about other customer use cases where this strategy is not adequate. Please contact us with more information about your specific needs.