Multithreaded Transfers

Multi-threaded transfer is a generic term that often causes confusion due to its inconsistent usage. A multi-threaded transfer is any transfer that uses multiple connections. Both parallel and segmented transfers, explained below, are forms of multi-threaded transfers. The confusion comes from most clients using this term to mean the same as parallel transfer.

Parallel Transfers

Any modern client should support parallel transfers. A parallel transfer is one in which multiple files are downloaded in parallel (i.e., at the same time). Downloading many files simultaneously can often increase FTP speeds because each file uses a separate connection. If a single connection is limited in speed, downloading in parallel should result in an overall transfer bandwidth of the speed of each individual connection multiplied by the number of parallel connections.

For example, a single file downloads at 100 KB/s, while your ISP provides for 1 MB/s. If you download 10 files in parallel, each file should be able to reach 100 KB/s resulting in a total download speed of 1 MB/s.

Segmented Transfers

A segmented transfer is one that downloads a single file using multiple connections, essentially by splitting it into multiple pieces. Downloading segments of a file simultaneously can often increase FTP speeds because each segment uses a separate connection. If a single connection is limited in speed, downloading in segments should result in an overall transfer bandwidth of the speed of each individual connection multiplied by the number of segments.

For example, a single file downloads at 100 KB/s, while your ISP provides for 1 MB/s. If you download the file using 10 segments, each segment should be able to reach 100 KB/s resulting in a total download speed of 1 MB/s.

Clients

Note: There is a free client called BitKinex that often gets brought up as an alternative for segmented downloading on Windows. This client has a number of problems known to cause issues for users. It is suggested that you do not use this client.

Windows

Mac OS X

Linux

Mozilla Firefox