os/docs/os/storage/using-zfs/index.md

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Using ZFS in RancherOS	os-default	os/configuration/storage/

Using ZFS

In order to start using ZFS, you'll need to first enable one of the persistent consoles and enable kernel headers.

$ sudo ros console switch ubuntu
$ sudo ros service enable kernel-headers
$ sudo ros service up -d kernel-headers
$ sudo ros service logs kernel-headers

When RancherOS console has reloaded, you will have logged into the persistent console. The current kernel headers will need to be downloaded using the ros service enable and the service will be started with ros service up -d kernel-headers.

You can make sure that the headers are in the right place by looking at the kernel-headers service logs.

Installing ZFS on Ubuntu Console

Based on the Ubuntu ZFS docs, you only need to install zfs package into the Ubuntu console to enable ZFS. All the other necessary packages will be installed as its dependencies.

$ sudo apt update
$ sudo apt install zfs

Then have a look at the zfs dmks build log file - which is likely to be a file similar to /var/lib/dkms/zfs/0.6.5.6/build/make.log.

Mounting ZFS filesystems on boot

In order for ZFS to load on boot, it needs to be added to modules list in the config. Prior to adding it to the list of modules, you'll need to check to see if there are other modules that are currently enabled.

# Check to see what modules currently exist
$ sudo ros config get rancher.modules
# Make sure to include any modules that were already enabled
$ sudo ros config set rancher.modules [zfs]

You will also need to have the zpool cache imported on boot:

[ -f /etc/zfs/zpool.cache ] && zpool import -c /etc/zfs/zpool.cache -a

A cloud-config runcmd instruction will do it for you:

# check current 'runcmd' list
$ sudo ros config get runcmd
[]
# add the command we need to run on boot
$ sudo ros config set runcmd "[[sh, -c, '[ -f /etc/zfs/zpool.cache ] && zpool import -c /etc/zfs/zpool.cache -a']]"

Using ZFS

After it's installed, it should be ready to use!

$ sudo modprobe zfs
$ sudo zpool list
$ sudo zpool create zpool1 /dev/<some-disk-dev>

To experiment with ZFS, you can create zpool backed by just ordinary files, not necessarily real block devices. In fact, you can mix storage devices in your ZFS pools; it's perfectly fine to create a zpool backed by real devices and ordinary files.

ZFS storage for Docker on RancherOS

First, you need to stop thedocker system service and wipe out /var/lib/docker folder:

$ sudo system-docker stop docker
$ sudo rm -rf /var/lib/docker/*

To enable ZFS as the storage driver for Docker, you'll need to create a ZFS filesystem for Docker and make sure it's mounted.

$ sudo zfs create zpool1/docker
$ sudo zfs list -o name,mountpoint,mounted

At this point you'll have a ZFS filesystem created and mounted at /zpool1/docker. According to Docker ZFS storage docs, if the Docker root dir is a ZFS filesystem, the Docker daemon will automatically use zfs as its storage driver.

Now you'll need to remove -s overlay (or any other storage driver) from the Docker daemon args to allow docker to automatically detect zfs.

$ sudo ros config set rancher.docker.storage_driver ''
$ sudo ros config set rancher.docker.graph /zpool1/docker
# After editing Docker daemon args, you'll need to start Docker
$ sudo system-docker stop docker
$ sudo system-docker start docker

After customizing the Docker daemon arguments and restarting docker system service, ZFS will be used as Docker storage driver:

$ docker info
Containers: 1
 Running: 0
 Paused: 0
 Stopped: 1
Images: 1
Server Version: 1.12.1
Storage Driver: zfs
 Zpool: zpool1
 Zpool Health: ONLINE
 Parent Dataset: zpool1/docker
 Space Used By Parent: 27761152
 Space Available: 4100088320
 Parent Quota: no
 Compression: off
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: host null bridge overlay
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Security Options: seccomp
Kernel Version: 4.4.16-rancher
Operating System: RancherOS v0.6.0-rc8
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 1.938 GiB
Name: rancher
ID: EK7Q:WTBH:33KR:UCRY:YAPI:N7RX:D25K:S7ZH:DRNY:ZJ3J:25XE:P3RF
Docker Root Dir: /zpool1/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Insecure Registries:
 127.0.0.0/8