BTRFS - Looks like it is time to make the move
When it comes to filesystems the most important thing that a server admin will be concerned about is stability, which will then limit the types of filesystems that they will consider. The time finally came for me to reconsider stability, because I ended up in a situation where I needed to have a filesystem that had native support for compression, without it being a feature that was added later on in the filesystem drivers life. The only filesystem that did fit the bill at the time was BTRFS, but I noticed that there were still people having problems with it, even in the stable kernels. I decided to use a stable kernel that seemed recent enough, but it turned out that there were still a few corner cases left behind. I was using a 3.14 stable kernel and it was handling all of its other duties without a problem, but I found that the server would freeze after about a week and a half, if the BTRFS filesystem was left mounted. I then had to dig into the internet to find out what was happening and found someone else who was having their server freeze after two weeks with the same kernel that I was using. I then had to dig into any posts relating directly to BTRFS development and I found one that indicated that Facebook were also having a similar problem, so had put their engineers onto the job and had merged a big patch-set into the 4.1 kernel. It might seem a bit strange that I was using a not fully stable filesystem on a production server at a clients, but I knew that the Linux kernel is very good at still working normally, even when one of its drivers is giving a problem, so I felt that it was worth the risk, with the certainty that the BTRFS driver would eventually stabilise. I finally had a chance to reboot the server, as stealth reboots would never work because the machine takes a full five minutes to go through the BIOS screens, because of all the hardware that is installed, then checked that the BTRFS filesystem would mount with the new driver. BTRFS also seems to have a stable filesystem format, because I did not have any file corruptions, after all of the hard reboots that the server had to go through. After a few months of solid uptime had gone by, I knew that BTRFS had finally arrived and it has even surprised me with the amount of space that seems to have been saved by its native file system compression scheme. So I can safely say that I will be using it in any server based backup systems that I have to setup, since I now know which is the best kernel to use to set the machine up with.