Typically random writes must first set a parity in doubt bit. In HW RAID that doesn’t require an additional write to a metadata location, but is instead maintai

Typically random writes must first set a parity in doubt bit. In HW RAID that doesn’t require an additional write to a metadata location, but is instead maintained in some nv memory. Similarly, a read modify write in software raid-5/6 have some poor trade offs. It’s common for a random write to perform a read of both the destination location, as well as the parity. This is followed by a write to the destination blocks and the parity blocks. What happens if power loss happens on the write? Maybe you get a torn page. HWRaid can protect against these surprisingly common failure modes. There are file systems which aren’t impacted by these failure modes, and software raid would be fine, but anything performing random writes, HWRaid has its place.