Disk Configuration Extension

The disk configuration extension adds the OS-DCF:diskConfig attribute to servers, which controls how the disk is partitioned when servers are created, rebuilt, or resized. A server gets the OS-DCF:diskConfig value from the image with which it was created, based on the image’s auto-disk-config attribute. To override the inherited setting, you can include the OS-DCF:diskConfig attribute in the request body of a server create, rebuild, or resize request.

Important

If an image has auto-disk-config value of MANUAL``or ``DISABLED, you cannot create a server from that image with a OS-DCF:diskConfig value of AUTO.

Valid OS-DCF:diskConfig values are:

• AUTO. The server is built with a single partition the size of the target flavor disk. The file system is automatically adjusted to fit the entire partition. This keeps things simple and automated. AUTO is valid only for images and servers with a single partition that use the EXT3 file system. This is the default setting for applicable Rackspace base images.

• MANUAL. The server is built using whatever partition scheme and file system is in the source image. If the target flavor disk is larger, the remaining disk space is left unpartitioned. This enables images to have non-EXT3 file systems, multiple partitions, and so on, and enables you to manage the disk configuration.

Note

Although Rackspace Windows images are configured with a auto-disk-config value of MANUAL, the NTFS file system expands to the entire partition on only the first boot.

Resizing down requires the server to have a OS-DCF:diskConfig value of AUTO.

The namespace for this extended attribute is:

xmlns:OS-DCF="http://docs.openstack.org/compute/ext/disk_config/api/v1.1"

Changes to Get Server/Image Details

A GET request on the /servers/detail, /servers/{id}, /images/detail, or /images/{id} resource returns the OS-DCF:diskConfig extended attribute. See the following operations:

• List Servers

• Show Server Details

• List Images

• Show Image Details

Changes to Rebuild Server

You can set the OS-DCF:diskConfig attribute when you rebuild a server. In the following examples, the OS-DCF:diskConfig attribute is set to MANUAL, which allows unused disk space to be used for other partitions after the server is rebuilt.

If you do not set the OS-DCF:diskConfig attribute is not set during the rebuild, the original value of the attribute is retained.

Example: Rebuild Server with OS-DCF:diskConfig: JSON Request

                    {
"rebuild" : {
         "name" : "new-server-test",
         "imageRef" : "d42f821e-c2d1-4796-9f07-af5ed7912d0e",
         "flavorRef" : "2",
         "OS-DCF:diskConfig" : "manual",
         "adminPass" : "diane123",
         "metadata" : {
              "My Server Name" : "Apache1"
               },
         "personality" : [
             {
               "path" : "/etc/banner.txt",
               "contents" : "ICAgICAgDQoiQSBjbG91ZCBkb2VzIG5vdCBrbm93IHdoeSBp dCBtb3ZlcyBpbiBqdXN0IHN1Y2ggYSBkaXJlY3Rpb24gYW5k IGF0IHN1Y2ggYSBzcGVlZC4uLkl0IGZlZWxzIGFuIGltcHVs c2lvbi4uLnRoaXMgaXMgdGhlIHBsYWNlIHRvIGdvIG5vdy4g QnV0IHRoZSBza3kga25vd3MgdGhlIHJlYXNvbnMgYW5kIHRo ZSBwYXR0ZXJucyBiZWhpbmQgYWxsIGNsb3VkcywgYW5kIHlv dSB3aWxsIGtub3csIHRvbywgd2hlbiB5b3UgbGlmdCB5b3Vy c2VsZiBoaWdoIGVub3VnaCB0byBzZWUgYmV5b25kIGhvcml6 b25zLiINCg0KLVJpY2hhcmQgQmFjaA=="
             }
           ]
    }
}

Changes to Resize Server

You can set the OS-DCF:diskConfig attribute when you resize a server, which enables you to change the value of the attribute when you scale a server up or down.

If you do not set the OS-DCF:diskConfig attribute during the resize, the original value of the attribute is retained.

Example: Resize Server with OS-DCF:diskConfig: JSON Request

                    {
    "resize" : {
        "flavorRef" : "3",
        "OS-DCF:diskConfig" : "manual"
    }
}

Changes to Create Server

When you create a server from an image with the auto-disk-config value set to TRUE, the server is built with a single partition that is expanded to the disk size of the flavor selected. If the image has the auto-disk-config value set to FALSE or DISABLED, the server is built by using the partition scheme and file system that is in the source image. If the target flavor disk is larger, remaining disk space is left unpartitioned. A server gets the OS-DCF:diskConfig attribute value from the image from which it is created, based on the image’s auto-disk-config attribute.

For an example of this operation, see Create server with disk config operation.