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There is a lot of material pointing out the dangers of using a loopback devices with the devicemapper driver. This question seems to contain most of the information necessary to move away from a loopback device.

Usage of loopback devices is strongly discouraged for production use

My question is how to create the volume group /dev/my-vg in Ubuntu? Or are there other paths around the loopback device that don't involve creating a volume group?

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  • Is there a specific reason you want to use devicemapper on Ubuntu? On Ubuntu, aufs is the default driver, and (in general) better performing. You will need to have `linux-image-extra` installed for it to work. – thaJeztah Feb 20 '16 at 23:42
  • Yeah, this issue is preventing me from building a meteor image (which depends on `npm install`) with aufs or overlay. https://github.com/npm/npm/issues/9863 – rissem Feb 20 '16 at 23:53
  • Also should mention that I tried the command at the bottom of https://jpetazzo.github.io/assets/2015-03-03-not-so-deep-dive-into-docker-storage-drivers.html#44 pointing to `/dev/sda1` and `/deb/sdb1` but see this in the logs on startup. `Error starting daemon: error initializing graphdriver: devicemapper: Error running deviceCreate (CreatePool) dm_task_run failed` – rissem Feb 21 '16 at 00:03
  • Hm, if you're unable to build an image using the aufs driver, I think you should open a bug report, as using aufs should not prevent you from building an image – thaJeztah Feb 21 '16 at 00:08
  • For setting up a devicemapper volume; have you tried the instructions in https://docs.docker.com/engine/userguide/storagedriver/device-mapper-driver/#configure-direct-lvm-mode-for-production – thaJeztah Feb 21 '16 at 00:08
  • I think it's just an issue with npm using rename instead of move as described in the above issue. That said I'm happy to open an issue on the docker repo if you think it could be fixed at the docker level. Thanks for pointing me to those instructions on the user guide. I'm stuck on step 3 as I'm not sure how to find a "spare block device" – rissem Feb 22 '16 at 03:05

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