Interacting with Block Storage (1.6)

The Block Storage Service in Eucalyptus is interface-compatible with Amazon's Elastic Block Store. You can therefore use either EC2 commands or euca2ools commands to control it.

The instructions below rely on the euca2ools command-line tools distributed by the Eucalyptus Team. Please, install them if you haven't done so already.

The following operations are possible,

1. Creating volumes

You may create a volume either from scratch or from an existing snapshot.

euca-create-volume --size <size> --zone <zone>

where <size> is the size in GB and <zone> is the availability zones you wish to create the volume in (use euca-describe-availability-zones to discover zones).

For instance,

euca-create-volume --size 1 --zone myzone

will create a 1GB volume in the availability zone "myzone"

To create a volume from a snapshot,

euca-create-volume --snapshot <snapshot id> --zone <zone>

where <snapshot id> is the unique identifier for a snapshot and <zone> is the availability zone you wish to create the volume in.

For instance,

euca-create-volume --snapshot --zone myzone snap-EF4323

will create a volume from the snapshot "snap-EF4323" in the zone "myzone"

2. Query the status of volumes

euca-describe-volumes

Volumes marked "available" are ready for use.

3. Attaching a volume

You can attach volumes to existing instances (that have been started with euca-run-instances). You may attach a volume to only one instance at a time.

euca-attach-volume -i <instance id> -d <local device name> <volume id>

where <volume id> is the unique identifier for a volume (vol-XXXX), <instance id> is a unique instance identifier and <local device name> is the name of the local device in the guest VM.

For instance,

euca-attach-volume -i i-345678 -d /dev/sdb vol-FG6578 

will attach the previously unattached volume "vol-FG6578" to instance "i-345678" with the local device name "/dev/sdb"

4. Detaching a volume

euca-detach-volume <volume id>

where <volume id> is the unique identifier for a previously attached volume (vol-XXXX).

For instance,

euca-detach-volume vol-FG6578

will detach volume "vol-FG6578"

Important! The user of the instance is responsible for making sure that the block device is unmounted before a detach. Detach cannot ensure the consistency of user data if the user detaches a volume that is in use.

5. Deleting a volume

euca-delete-volume <volume id>

where <volume id> is the unique identifier for a volume (vol-XXXX).

6. Creating a snapshot from a volume

You can snapshot a volume so that you can create volumes in the future from the snapshot.

euca-create-snapshot <volume id>

where <volume id> is the unique identifier for a volume (vol-XXXX).

For instance,

euca-create-snapshot vol-GH4342

will snapshot the volume "vol-GH4342"

The volume to be snapshotted needs to be "available" or "in-use." You cannot snapshot a volume that is in the "creating" state.

7. Querying the status of snapshots

euca-describe-snapshots

You may create volumes from snapshots that are marked "completed."

8. Deleting a snapshot

euca-delete-snapshot <snapshot id>

where <snapshot id> is the unique identifier for a snapshot.