openstack/glance
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Add disk format content from Image Guide

Browse Source 
The container_format and disk_format identifiers and their
descriptions are being maintained in the Glance docs.  Move some
useful content on this topic over from the Image Guide before
deleting it over there so it's only being maintained in one
location.

Change-Id: Ifa8de9d3a3a2aa78ee305aaebb23cd982b02dd91
Partial-bug: #1842343
This commit is contained in:
Brian Rosmaita 2019-09-02 21:14:02 -04:00
parent 85a91ba143
commit c3e0b8436a
1 changed files with 60 additions and 22 deletions
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82
doc/source/user/formats.rst
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@ -36,51 +36,79 @@ You can set your image's disk format to one of the following:
* **raw**
This is an unstructured disk image format
This is an unstructured disk image format.
The ``raw`` image format is the simplest one, and is natively supported by
both KVM and Xen hypervisors. You can think of a raw image as being the
bit-equivalent of a block device file, created as if somebody had copied,
say, ``/dev/sda`` to a file using the :command:`dd` command.
* **vhd**
This is the VHD disk format, a common disk format used by virtual machine
monitors from VMware, Xen, Microsoft, VirtualBox, and others
This is the VHD (Virtual Hard Disk) disk format, a common disk format used by
virtual machine monitors from VMware, Xen, Microsoft, VirtualBox, and others.
* **vhdx**
This is the VHDX disk format, an enhanced version of the vhd format which
supports larger disk sizes among other features.
This is the `VHDX
<http://technet.microsoft.com/en-us/library/hh831446.aspx>`_ format, an
enhanced version of the ``vhd`` format. It has support for larger disk sizes
and protection against data corruption during power failures.
* **vmdk**
Another common disk format supported by many common virtual machine monitors
The
`VMDK <https://developercenter.vmware.com/web/sdk/60/vddk>`_
(Virtual Machine Disk) format is supported by many common virtual machine
monitors, for example the VMware ESXi hypervisor.
* **vdi**
A disk format supported by VirtualBox virtual machine monitor and the QEMU
emulator
The `VDI <https://forums.virtualbox.org/viewtopic.php?t=8046>`_
(Virtual Disk Image) format for image files is supported by the VirtualBox
virtual machine monitor and the QEMU emulator.
* **iso**
An archive format for the data contents of an optical disc (e.g. CDROM).
The `ISO
<http://www.ecma-international.org/publications/standards/Ecma-119.htm>`_
format is a disk image formatted with the read-only ISO 9660 (also known
as ECMA-119) filesystem commonly used for CDs and DVDs.
* **ploop**
A disk format supported and used by Virtuozzo to run OS Containers
A disk format supported and used by Virtuozzo to run OS Containers.
* **qcow2**
A disk format supported by the QEMU emulator that can expand dynamically and
supports Copy on Write
The `QCOW2 <http://en.wikibooks.org/wiki/QEMU/Images>`_
(QEMU copy-on-write version 2) format is commonly used with the
KVM hypervisor. It uses a sparse representation, so the image size
is smaller than a raw format file of the same virtual disk. It can
expand dynamically and supports Copy on Write.
The `AKI/AMI/ARI
<http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AMIs.html>`_
format was the initial image format supported by Amazon EC2.
The image consists of three files, each of which has its own specific
``disk_format`` identifier:
* **aki**
This indicates what is stored in Glance is an Amazon kernel image
This indicates what is stored in Glance is an Amazon Kernel Image (AKI).
It is a kernel file that the hypervisor will load initially to boot the
image. For a Linux machine, this would be a ``vmlinuz`` file.
* **ari**
This indicates what is stored in Glance is an Amazon ramdisk image
This indicates what is stored in Glance is an Amazon Ramdisk Image (ARI).
It is an optional ramdisk file mounted at boot time.
For a Linux machine, this would be an ``initrd`` file.
* **ami**
This indicates what is stored in Glance is an Amazon machine image
This indicates what is stored in Glance is an Amazon Machine Image (AMI).
It is a virtual machine image in raw format.
Container Format
----------------
@ -103,32 +131,42 @@ You can set your image's container format to one of the following:
* **bare**
This indicates there is no container or metadata envelope for the image
This indicates there is no container or metadata envelope for the image.
* **ovf**
This is the OVF container format
`OVF <http://dmtf.org/sites/default/files/OVF_Overview_Document_2010.pdf>`_
(Open Virtualization Format) is a packaging format for virtual machines,
defined by the Distributed Management Task Force (DMTF) standards group.
An OVF package contains one or more image files, a ``.ovf`` XML metadata file
that contains information about the virtual machine, and possibly other
files as well.
An OVF package can be distributed in different ways. For example,
it could be distributed as a set of discrete files, or as a tar archive
file with an ``.ova`` (open virtual appliance/application) extension.
* **aki**
This indicates what is stored in Glance is an Amazon kernel image
This indicates what is stored in Glance is an Amazon kernel image.
* **ari**
This indicates what is stored in Glance is an Amazon ramdisk image
This indicates what is stored in Glance is an Amazon ramdisk image.
* **ami**
This indicates what is stored in Glance is an Amazon machine image
This indicates what is stored in Glance is an Amazon machine image.
* **ova**
This indicates what is stored in Glance is an OVA tar archive file
This indicates what is stored in Glance is an OVA tar archive file,
that is, an OVF package contained in a single tar archive file.
* **docker**
This indicates what is stored in Glance is a Docker tar archive of
the container filesystem
the container filesystem.
* **compressed**