Random read / write speed
Operating systems often issue many small, random I/O operations. This is even more true when you put many OS onto one single server. In this case, random I/O speed become a crucial parameter. How well the contenders fare in this workload?
First, random read:
As you can see, while BTRFS is the slowest again, it is not so much behind the others. EXT3, EXT4 and XFS are again basically tied.
Now, random write:
We see a very different picture now: BTRFS is way, way slower then the others. EXT3 and EXT4 are tied, with XFS showing a great score when dealing with low queue dept (the usual case). On the other hand, when dealing with higher queue dept (a not so common scenario on guest virtual machines), XFS slow down considerably, even falling slightly behind EXT3/4.