In OpenStack, the base operating system is usually copied from an image stored in the OpenStack Image Service. This is the most common case and results in an ephemeral instance that starts from a known template state and loses all accumulated states on shutdown.
You can also put an operating system on a persistent volume in Compute or the Block Storage volume system. This gives a more traditional, persistent system that accumulates states, which are preserved across restarts. To get a list of available images on your system, run:
$ nova image-list +--------------------------------------+-------------------------------+--------+--------------------------------------+ | ID | Name | Status | Server | +--------------------------------------+-------------------------------+--------+--------------------------------------+ | aee1d242-730f-431f-88c1-87630c0f07ba | Ubuntu 12.04 cloudimg amd64 | ACTIVE | | | 0b27baa1-0ca6-49a7-b3f4-48388e440245 | Ubuntu 12.10 cloudimg amd64 | ACTIVE | | | df8d56fc-9cea-4dfd-a8d3-28764de3cb08 | jenkins | ACTIVE | | +--------------------------------------+-------------------------------+--------+--------------------------------------+
The displayed image attributes are:
IDAutomatically generated UUID of the image.
NameFree form, human-readable name for image.
StatusThe status of the image. Images marked
ACTIVEare available for use.ServerFor images that are created as snapshots of running instances, this is the UUID of the instance the snapshot derives from. For uploaded images, this field is blank.
Virtual hardware templates are called flavors. The default
installation provides five flavors. By default, these are configurable by administrative
users. However, you can change this behavior by redefining the access controls for
compute_extension:flavormanage in
/etc/nova/policy.json on the compute-api
server.
For a list of flavors that are available on your system, run:
$ nova flavor-list +----+-----------+-----------+------+-----------+------+-------+-------------+ | ID | Name | Memory_MB | Disk | Ephemeral | Swap | VCPUs | RXTX_Factor | +----+-----------+-----------+------+-----------+------+-------+-------------+ | 1 | m1.tiny | 512 | 1 | N/A | 0 | 1 | | | 2 | m1.small | 2048 | 20 | N/A | 0 | 1 | | | 3 | m1.medium | 4096 | 40 | N/A | 0 | 2 | | | 4 | m1.large | 8192 | 80 | N/A | 0 | 4 | | | 5 | m1.xlarge | 16384 | 160 | N/A | 0 | 8 | | +----+-----------+-----------+------+-----------+------+-------+-------------+
