For his PhD thesis, he co-developed rsync, including the rsync algorithm, a highly efficient file transfer and synchronization tool. He also was the original author of rzip, which uses a similar algorithm to rsync.
In April 2005, Tridgell tried to produce free software (now known as SourcePuller) that interoperated with the BitKeeper source code repository. It was a source of controversy and was cited as the reason that BitMover revoked the license that allowed Linux developers free usage of their BitKeeper product. This resulted in a messy public falling-out between Tridgell and Linus Torvalds, in which Tridgell stated that he had never had a BitKeeper license so he couldn't violate it and had acted entirely ethically in analysing and implementing the protocol, something he'd previously done with the Samba protocol. Tridgell's involvement in the project resulted in Linus accusing him of playing dirty tricks with BitKeeper.
The broad extent of Tridgell's analysis started by ing to a BitKeeper server and typing
HELP, something that, seemingly, no-one else had previously thought to try.
Tridgell completed a PhD at the Computer Sciences Laboratory of the Australian National University. His original doctorate work was in the area of speech recognition but was never completed. His submitted thesis 'Efficient Algorithms for Sorting and Synchronization' was based on his work on the rsync algorithm.
From 1988 to 1989, Tridgell worked as a software developer for a company named Sonartech Pty Ltd (now Sonartech Atlas), which developed sonar technologies for Australian submarines. He worked on passive sonar technology.
Between 1989 and 1990, Tridgell was employed at the Research School of Biological Sciences in the Australian National University, making computer models of physical and biological events and environments such as bushfire spread and population dynamics.
From 1991 to 1999, Tridgell held various other positions at the Australian National University, such as UNIX administration, satellite control, and supercomputer research. During this period he was seconded to the Cooperative Research Centre for Advanced Computational Systems, where he headed the PIOuS (Parallel Input/Output System) project - later HiDIOS (High-performance Distributed Input/Output System) - for parallel file systems on the Fujitsu AP1000 and AP+ supercomputers. Tridgell also went on to lecture, first as an associate lecturer, and then as a casual lecturer, in the university's Computer Science division. He remains a Visiting Fellow of the University.
In mid-1999, Tridgell joined the LinuxCare company's office in Canberra as their first Australian employee. He helped to assemble 14 staff for a research and development team known as OzLabs. Linux and open-source companies were quite a new concept at this stage. Tridgell was made a research fellow of Linuxcare in 2000.
In March 2001, Tridgell joined VA Linux Systems. He worked in the network attached storage division for VA Linux Systems, making enhancements to Samba and the Linux kernel to provide enhanced performance for their network-attached storage device range.
Tridgell continued his work with network-attached storage technologies when he joined Quantum Corporation as a Senior Engineer in the Storage Systems Group. His role once again involved developing functionality and efficiency modifications into Samba to enhance Quantum's GuardianOS-powered Snap Server network-attached storage device. One of the features that he added to Samba at this time was support for Microsoft's Active Directory technology, a new authentication system introduced with Microsoft's Windows 2000 Server product range.