docker/devicemapper/devicemapper/data confusing rsync

[alfredopalhares]

Hello everyone,

I just bought a brand new SSD and I was migrating my data to a new disk, the usual way is to just set the boot partition, LUKS and LVM, rsync the whole system re-run syslinux and I am good to go.

This is the exact rsync command I run:

sudo rsync -aAXv --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found"} --progress /* root@192.168.2.2:/mnt

This was all going fine, until it start copying the file /var/lib/docker/devicemapper/devicemapper/data which seemed huge, until rsync gave me a "No more space left on device" error, while the new hard drive wasn't getting any more data (this while copying the devicemapper/data file).

I've tried to ls the file, but there is nothing on that path.

I had to add the path to the exclude directory of rsync to get a full system move.

What does this file do ? And why does rsync seem to behave like while copying it ?

Regards,
Alfredo Palhares

[GordonTheTurtle]

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[alfredopalhares]

Adding --sparse to the above rsync command, makes rsync ignore sparse files.

[OwenChia]

Just issues the same question.
I have tried using --sparse, it's seems work. But now I can not start docker service.

Here is the log:

Jul 18 14:18:39 Inspiron systemd[1]: Starting Docker Application Container Engine...
-- Subject: Unit docker.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit docker.service has begun starting up.
Jul 18 14:18:39 Inspiron dockerd[30681]: time="2016-07-18T14:18:39.457936679+08:00" level=info msg="New containerd process, pid: 30701"
Jul 18 14:18:40 Inspiron dockerd[30681]: time="2016-07-18T14:18:40.477497302+08:00" level=error msg="[graphdriver] prior storage driver \"devicemapper\" failed: devmapper: Unable to find loopback mount for: /var/lib/docker/devicemapper/devicemapper/data"
Jul 18 14:18:40 Inspiron dockerd[30681]: time="2016-07-18T14:18:40.477637412+08:00" level=fatal msg="Error starting daemon: error initializing graphdriver: devmapper: Unable to find loopback mount for: /var/lib/docker/devicemapper/devicemapper/data"
Jul 18 14:18:40 Inspiron systemd[1]: docker.service: Main process exited, code=exited, status=1/FAILURE
Jul 18 14:18:40 Inspiron systemd[1]: Failed to start Docker Application Container Engine.
-- Subject: Unit docker.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit docker.service has failed.
-- 
-- The result is failed.
Jul 18 14:18:40 Inspiron systemd[1]: docker.service: Unit entered failed state.
Jul 18 14:18:40 Inspiron systemd[1]: docker.service: Failed with result 'exit-code'.
Jul 18 14:18:40 Inspiron polkitd[569]: Unregistered Authentication Agent for unix-process:30668:665262 (system bus name :1.121, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.utf8) (disconnected from bus)

[shegeley]

I spent about 3 hours today trying to figure out how to move all the docker data to my Digital Ocean attached volume.

Complete Ubuntu 16.04 instruction

sudo service docker stop
sudo cd /var/lib
sudo rsync -v --sparse  docker  /your/path

sudo rm -rf docker
sudo ln -s docker /your/path

sudo vim /etc/default/docker

Make sure to uncomment the line and paste:
DOCKER_OPTS="--dns 8.8.8.8 --dns 8.8.4.4 -g /your/path"

Then:
sudo vim /lib/systemd/system/docker.service
Make sure Exec Start looks like:
ExecStart=/usr/bin/docker daemon -H fd:// -g /your/path

FINALLY:

systemctl daemon-reload
service docker start

🙌

[tedgoldstein]

Two comments.

1. You have the symbolic link command backwards. It should be:

sudo ln -s /your/path docker

2. You don't really need to reconfigure the DOCKER_OPTS because it happily goes through the symbolic link.

[thaJeztah]

The devicemapper storage-driver was deprecated, and has been removed, so closing issues related to this storage-driver. See;

• Deprecate "devicemapper" storage driver, and add warning #38017
• Remove deprecated devicemapper storage driver #43637