File System Selection
The file system selection is one of the most crucial factors of your GroupWise system. GroupWise is extremely intense with disk read/write activity, and you need a file system that can perform under stress.
Historically Significant Trivia
A GroupWise system can easily have hundreds of thousands, or even millions of files within the various folder structures. This can create challenges because the file system has to quickly search, index, and read/write to these folders constantly. Additionally, the majority of the files are relatively small. If the file system is not designed to handle millions of small files, it can suffer dramatically as the system grows.
In the earlier years with SLES 10, ReiserFS was well known as the preferred file system for GroupWise running on Linux. It was fast and handled lots of small files with relative ease. But when the main developer of the ReiserFS, Hans Reiser, murdered his wife and went to prison, ReiserFS was essentially cancelled. This led to the need to embrace a new file system. Unfortunately, the best option at the time seemed to be EXT3.
EXT3 became the file system that most people started using. They didn't have a choice. But EXT3 is horrible with larger file systems and resulted in severe performance issues as GroupWise systems grew. In fact, the EXT3 file system worked so poorly that if I had to choose between EXT3 and NSS, I would choose NSS every time. Even though I don't like the extra overhead with NSS, it is designed to handle massive file systems and does a pretty decent job.
Linux Servers, including SLES and OES
With Linux, including OES, you have a few different options for the file system. I prefer and strongly recommend the XFS file system. However I will outline each of the main ones below:
EXT3 Caveat for in-place upgrades.
Let's say you are running GroupWise on an old SLES 11 server, and it's using EXT3. While you could possibly upgrade to SLES12 in place, and then upgrade GroupWise to GroupWise 2018, this is one situation that I would avoid. While it is supported and would be functional, your file system will still be using EXT3, an inferior file system. A better option would be to build a new SLES 15 server with the XFS file system and do a full data migration.
Your only option on Windows is the NTFS file system. It's true that Windows 2019 has another file system, ReFS (Introduced with Windows 2012 and improved with Windows 2019), however it is unclear whether this is a viable option.