What is the difference between AUFS and devicemapper in docker?

Question

When docker was introduced a big hype was made about docker using AUFS, allowing two different docker containers to use the same underlying layers, and thus reducing some of the overhead. Docker now seems to prefer devicemapper (eg default in Ubuntu 14.04). Does devicemapper provide the same functionality, or did people figure out that the advantages are not too big using AUFS ?

Answer 1

This article details the differences between the storage backends available to docker. Devicemapper support was implemented since AUFS is not included in the kernel and thus was only available on systems (such as Ubuntu) that provided it. Because of this it is generally not recommended in production environments.

Answer 2

No, devicemapper does not provide the same functionality -- it's much, much slower; since it operates at the block-device layer, it needs to deal with mounting, unmounting, fsck'ing, etc.

The reason it's widely used is that many distributions' kernels do not support AUFS. However, if you can use AUFS, you probably should .