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149 lines
4.5 KiB
Markdown
149 lines
4.5 KiB
Markdown
# External Disk
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`linuxkit run` has the ability to mount an external disk when booting. It involves two steps:
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1. Make the disk available as a device
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2. Mount the disk
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## Make Disk Available
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In order to make the disk available, you need to tell `linuxkit` where the disk file or block device is.
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All local `linuxkit run` methods (currently `hyperkit`, `qemu`, `virtualization.framework` and `vmware`)
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take a `-disk` argument:
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* `-disk path,size=100M,format=qcow2`. For size the default is in GB but an `M` can be appended to specify sizes in MB. The format can be omitted for the platform default, and is only useful on `qemu` at present.
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If a _path_ is specified `linuxkit` will use the disk at location _path_. If you do not provide `-disk ` _path_, `linuxkit` assumes a default path, which is _prefix_`-state/disk.img`.
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If the disk at the specified or default _path_ does not exist, `linuxkit` will create one of size _size_.
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The `-disk` specification may be repeated for multiple disks, although a limited number may be supported, and some platforms currently only support a single disk.
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**TODO:** GCP
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## Format the disk
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`pkg/format` creates a partition table and format drives for use with LinuxKit
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### Example Usage
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This packages supports two modes of use:
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```
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onboot:
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- name: format
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image: linuxkit/format:<hash>
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```
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In this mode of operation, the first disk found that does not have a valid partition table
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will have one linux partition created that fills the entire disk
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### Options
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```
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onboot:
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- name: format
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image: linuxkit/format:<hash>
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command: ["/usr/bin/format", "-type", "ext4", "-label", "DATA", "/dev/vda"]
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```
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```
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onboot:
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- name: format
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image: linuxkit/format:<hash>
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command: ["/usr/bin/format", "-force", "-type", "xfs", "-label", "DATA", "-verbose", "/dev/vda"]
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```
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```
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onboot:
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- name: format
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image: linuxkit/format:<hash>
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command: ["/usr/bin/format", "-type", "ext4", "-partition", "gpt", "/dev/vda"]
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```
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- `-force` can be used to force the partition to be cleared and recreated (if applicable), and the recreated partition formatted. This option would be used to re-init the partition on every boot, rather than persisting the partition between boots.
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- `-label` can be used to give the disk a label
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- `-type` can be used to specify the type. This is `ext4` by default but `btrfs` and `xfs` are also supported
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- `-partition` can be used to specify the partition table type. This is `dos` by default but `gpt` is also supported
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- `-verbose` enables verbose logging, which can be used to troubleshoot device auto-detection and (re-)partitioning
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- The final (optional) argument specifies the device name
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## Mount the disk
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Once a disk has been prepared it will need to be mounted using `pkg/mount`
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### Usage
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**NOTE: Block devices may only be mounted in `/var` unless you have explicitly added an additional bind mount**
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If no additional arguments are provided the first unmounted linux partition on the first block device is mounted to the mountpoint provided.
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```
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onboot:
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- name: mount
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image: linuxkit/mount:<hash>
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command: ["/usr/bin/mountie", "/var/lib/docker"]
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```
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### Options
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You can provide either a partition label, device name or disk UUID to specify which disk should be used.
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For example:
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```
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onboot:
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- name: mount
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image: linuxkit/mount:<hash>
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command: ["/usr/bin/mountie", "-label", "DATA", "/var/lib/docker" ]
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```
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```
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onboot:
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- name: mount
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image: linuxkit/mount:<hash>
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command: ["/usr/bin/mountie", "-uuid", "a-proper-uuid", "/var/lib/docker" ]
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```
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```
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onboot:
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- name: mount
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image: linuxkit/mount:<hash>
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command: ["/usr/bin/mountie", "-device", "/dev/sda1", "/var/lib/docker" ]
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```
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For compatibility with the standard `mount` command we also support providing the device name as a positional argument.
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E.g
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```
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onboot:
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- name: mount
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image: linuxkit/mount:<hash>
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command: ["/usr/bin/mountie", "/dev/sda1", "/var/lib/docker" ]
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```
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## Extending Partitions
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`pkg/extend` can extends a single partition to fill the entire disk
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### Usage
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In the default mode of operation, any disks that are found and have a single partition and free space will have that partition extended.
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```
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onboot:
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- name: extend
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image: linuxkit/extend:<hash>
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```
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### Options
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`-type` can be used to specify the type. The default is `ext4` but `btrfs` and `xfs` are also supported.
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If you know the name of the disk that you wish to extend you may supply this as an argument
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```
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onboot:
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- name: extend
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image: linuxkit/extend:<hash>
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command: ["/usr/bin/extend", "-type", "btrfs", "/dev/vda"]
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```
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