AISBackup enables manual transfer of FTP backup data using a portable device. Here is an extract from the AISBackup help file - I hope it helps
FTP Manually Transferring the Backup.
Some backup's can be quite large and may take a long time to transfer using FTP, this is where AISBackup's ability to only backup differences since the last backup is useful. However, the first backup session could be rather large and you may prefer to make arrangements to manually transfer the data to the FTP server using an external disk drive. AISBackup enabled this option with the Enable manual transfer option which may be set by using the menu option
Manage Backup / Change Backup Job Settings / FTP Settings.
Running the backup.
If the Enable manual transfer option is set AISBackup asks the Question Prepare backup for manual transfer rather than using FTP? when Run Backup is selected, answer No to proceed normally, answer Yes to create a local backup suitable for transferring to the FTP Server. Please note that access to the FTP server must be maintained because AISBackup creates flag file on the remote server to register that a manual transfer is pending.
Transferring the backup.
Once the backup has completed transfer the files from the local backup folder to an external drive, and then from there to the actual FTP folder. Ensure that the file named
ManualTransferComplete.sem is copied as this file, along with the FTP based file
WaitingForManualTransfer.sem indicate that the manual transfer is complete. AISBackup will automatically remove both these files during the next backup session.
What to transfer?
Even though the whole of the local PC copy of the backup may be transferred to the FTP Server the file
ftptransferlist.txt contains the list of files which must be manually copied to the server.
to do the first locally (ca.20GB 
) and the incrementals later by FTP. 