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Chapter 3. Cloud Infrastructure Concepts
14
• Dell EqualLogic™ for iSCSI
• Network Appliances filers for NFS and iSCSI
• Scale Computing for NFS
If you intend to use only local disk for your installation, you can skip adding separate primary storage.
3.7. About Secondary Storage
Secondary storage stores the following:
• Templates — OS images that can be used to boot VMs and can include additional configuration
information, such as installed applications
• ISO images — disc images containing data or bootable media for operating systems
• Disk volume snapshots — saved copies of VM data which can be used for data recovery or to
create new templates
The items in secondary storage are available to all hosts in the scope of the secondary storage, which
may be defined as per zone or per region.
CloudPlatform manages the allocation of guest virtual disks to particular primary storage devices.
To make items in secondary storage available to all hosts throughout the cloud, you can add object
storage in addition to the zone-based NFS Secondary Staging Store. It is not necessary to copy
templates and snapshots from one zone to another, as would be required when using zone NFS
alone. Everything is available everywhere.
Object storage is provided through third-party software such as Amazon Simple Storage Service (S3)
or any other object storage that supports the S3 interface. Additional third party object storages can be
integrated with CloudPlatform by writing plugin software that uses the object storage plugin capability.
CloudPlatform provides some plugins which we have already written for you using this storage plugin
capability. The provided plugins are for OpenStack Object Storage (Swift, swift.openstack.org
1
)
and Amazon Simple Storage Service (S3) object storage. The S3 plugin can be used for any object
storage that supports the Amazon S3 interface. When using one of these storage plugins, you
configure Swift or S3 storage for the entire CloudPlatform, then set up the NFS Secondary Staging
Store for each zone. The NFS storage in each zone acts as a staging area through which all templates
and other secondary storage data pass before being forwarded to Swift or S3. The backing object
storage acts as a cloud-wide resource, making templates and other data available to any zone in the
cloud.
There is no hierarchy in the Swift storage, just one Swift container per storage object. Any secondary
storage in the whole cloud can pull a container from Swift at need.
3.8. About Physical Networks
Part of adding a zone is setting up the physical network. One or (in an advanced zone) more physical
networks can be associated with each zone. The network corresponds to a NIC on the hypervisor
host. Each physical network can carry one or more types of network traffic. The choices of traffic
1
http://swift.openstack.org