docs: drop dated comments about graphdrivers

Signed-off-by: Bjorn Neergaard <bneergaard@mirantis.com>
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Bjorn Neergaard 2023-02-09 23:26:02 -07:00
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@ -295,57 +295,11 @@ $ docker -H tcp://127.0.0.1:2375 pull ubuntu
On Linux, the Docker daemon has support for several different image layer storage
drivers: `aufs`, `devicemapper`, `btrfs`, `zfs`, `overlay`, `overlay2`, and `fuse-overlayfs`.
The `aufs` driver is the oldest, but is based on a Linux kernel patch-set that
is unlikely to be merged into the main kernel. These are also known to cause
some serious kernel crashes. However `aufs` allows containers to share
executable and shared library memory, so is a useful choice when running
thousands of containers with the same program or libraries.
`overlay2` is the preferred storage driver for all currently supported Linux distributions,
and is selected by default. Unless users have a strong reason to prefer another storage driver,
`overlay2` should be used.
The `devicemapper` driver uses thin provisioning and Copy on Write (CoW)
snapshots. For each devicemapper graph location typically
`/var/lib/docker/devicemapper` a thin pool is created based on two block
devices, one for data and one for metadata. By default, these block devices
are created automatically by using loopback mounts of automatically created
sparse files. Refer to [Devicemapper options](#devicemapper-options) below
for a way how to customize this setup.
[~jpetazzo/Resizing Docker containers with the Device Mapper plugin](https://jpetazzo.github.io/2014/01/29/docker-device-mapper-resize/)
article explains how to tune your existing setup without the use of options.
The `btrfs` driver is very fast for `docker build` - but like `devicemapper`
does not share executable memory between devices. Use
`dockerd --storage-driver btrfs --data-root /mnt/btrfs_partition`.
The `zfs` driver is probably not as fast as `btrfs` but has a longer track record
on stability. Thanks to `Single Copy ARC` shared blocks between clones will be
cached only once. Use `dockerd -s zfs`. To select a different zfs filesystem
set `zfs.fsname` option as described in [ZFS options](#zfs-options).
The `overlay` is a very fast union filesystem. It is now merged in the main
Linux kernel as of [3.18.0](https://lkml.org/lkml/2014/10/26/137). `overlay`
also supports page cache sharing, this means multiple containers accessing
the same file can share a single page cache entry (or entries), it makes
`overlay` as efficient with memory as `aufs` driver. Call `dockerd -s overlay`
to use it.
The `overlay2` uses the same fast union filesystem but takes advantage of
[additional features](https://lkml.org/lkml/2015/2/11/106) added in Linux
kernel 4.0 to avoid excessive inode consumption. Call `dockerd -s overlay2`
to use it.
> **Note**
>
> The `overlay` storage driver can cause excessive inode consumption (especially
> as the number of images grows). We recommend using the `overlay2` storage
> driver instead.
> **Note**
>
> Both `overlay` and `overlay2` are currently unsupported on `btrfs`
> or any Copy on Write filesystem and should only be used over `ext4` partitions.
The `fuse-overlayfs` driver is similar to `overlay2` but works in userspace.
The `fuse-overlayfs` driver is expected to be used for [Rootless mode](https://docs.docker.com/engine/security/rootless/).
You can find out more about storage drivers and how to select one in [Select a storage driver](https://docs.docker.com/storage/storagedriver/select-storage-driver/).
On Windows, the Docker daemon only supports the `windowsfilter` storage driver.