md is the normal tool for doing RAID in software on Linux. It exposes a number of physical devices as one block device, which looks just like a normal hard disk.
btrfs is also a volume manager with RAID-like functionality of its own. But you can also use btrfs on an md device, just like you would with any other filesystem.
Software RAID is something I have only used for personal use, and with the enormous consumer hard drives available now, striping them seems less necessary than before.
Ahhhhh I though it was some sort of btrfs specific thing -- didn't recognize it as the 'md' in 'mdadm' (I've only dealt with software RAID before).
This is actually pretty interesting because one of the 'features' of the hosting provider I'm using is that they will software RAID your drives by default. Maybe btrfs is a better choice in that kind of environment if I don't have to undo the software raid on every machine and btrfs will interop well without too much abstraction.
btrfs is also a volume manager with RAID-like functionality of its own. But you can also use btrfs on an md device, just like you would with any other filesystem.
Software RAID is something I have only used for personal use, and with the enormous consumer hard drives available now, striping them seems less necessary than before.