Some sites run an FTP server on the same computer as MOVEit Central. Remote servers or mainframes send files to MOVEit Central via FTP, and MOVEit Central tasks process the files. (Typically, for better performance and reliability, the local FTP directory is configured as a filesystem source rather than an FTP source.)
In a failover scenario, this presents two types of problems:
If MOVEit Central server A fails after some files have been sent to MOVEit Central but before the related task runs, those files will not be transferred when the secondary B takes over, because they are on the failed computer. (Admittedly, if MOVEit Central has been set to use filesystem notifications, this time window will be very short.) Furthermore, if the new primary B fails days, weeks, or months later, the old, unprocessed files on server A may be processed when it becomes the primary. Depending on how tasks are configured, this may cause obsolete files to be sent, confusing the recipient.
Remote processes which have been programmed to send files to FTP server A may not be smart enough to send them to FTP server B if A is down.
These problems can be addressed with features built into Microsoft Windows which allow you to create a single system image from two FTP servers:
Distributed File System can be used to create a single storage area into which files FTPed to either MOVEit Central computer will be stored. See FTP Replication - DFS.
Network Load Balancing can be used to assign a single IP address which can be used by remote computers to access either FTP server as if the two were a single computer. See FTP Replication - NLB.
