We are currently using Titan FTP Server, but we have found that it has a memory leak. It also seems to fail two to three times a week during high load periods causing problems for our clients. When the Titan FTP Server fails, rebooting the actual (hardware) server seems to be the only way to fix the problem. When we have upgraded to their latest server code the problem becomes much worse. I have also tried working with their customer support and they have not been able to resolve the issue.
Hence, we are looking to replace the Titan FTP Server with another commercial grade FTP Server. We do all file transfers using SFTP and SFTP capability is a requirement. We transfer files to and from a large number of clients and the file sizes range from fairly small to 20MB. At peak times we may have 40 or more clients connected and either uploading or downloading files to the server.
Our environment is Windows Server 2008 Standard running on a 64 bit machine with 32GB of memory.