======CHPC Cloud Resources======


    *[[guide:cloud:overview|Overview]]
    *[[guide:cloud:start|Getting Started]]
    *[[guide:cloud|User Guide]]
    *[[guide:cloud:practices|Best Practice and Policies]]
    *[[guide:cloud:glossary|Glossary of Terms]]
    *[[guide:cloud:faq|FAQs]]

======Glossary of Terms======

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**Availability zone** - An Amazon EC2 concept of an isolated area that is used for fault tolerance. Do not confuse with an OpenStack Compute zone or cell. Availability Zones are an end-user visible logical abstraction for partitioning a cloud without knowing the physical infrastructure.

**CIDR** - representation (<IP>/<prefix length>) of the network’s IP subnet.

**CEPH** - Massively scalable distributed storage system that consists of an object store, block store, and POSIX-compatible distributed file system. Compatible with OpenStack.

**Port**  - A virtual network port within Networking; VIFs / vNICs are connected to a port.

**Ingress** -  The process of filtering incoming network traffic. Supported by Compute.

**Ephemeral volume** - Volume that does not save the changes made to it and reverts to its original state when the current user relinquishes control.

**External Network** - A network segment typically used for instance Internet access.

**Floating IPs**  - An IP address that a project can associate with a VM so that the instance has the same   public IP address each time that it boots. You create a pool of floating IP addresses and assign them to instances as they are launched to maintain a consistent IP address for maintaining DNS assignment.

**Flavor** - is an available hardware configuration for a VM instance. It defines the size of a virtual server that can be launched. Flavors define the compute, memory, and storage capacity of nova computing instances.

**GateWay IP** - An IP address, typically assigned to a router, that passes network traffic between different networks.

**Instances** - A running VM, or a VM in a known state such as suspended, that can be used like a hardware server.

**Images** - A collection of files for a specific operating system (OS) that you use to create or rebuild a server. OpenStack provides pre-built images. You can also create custom images, or snapshots, from servers that you have launched. Custom images can be used for data backups or as images for additional servers.

**Key pairs** - are SSH credentials that are injected into an instance when it is launched.A key pair belongs to an individual user, not to a project. To share a key pair across multiple users, each user needs to import that key pair.

**Live migration** - The ability within Compute to move running virtual machine instances from one host to another with only a small service interruption during switchover.

**Network** - A virtual network that provides connectivity between entities. For example, a collection of virtual ports that share network connectivity. In Networking terminology, a network is always a layer-2 network.

**Openstack** - is a cloud operating system that controls large pools of compute, storage, and networking resources throughout a data center, all managed through a dashboard that gives administrators control while empowering their users to provision resources through a web interface. OpenStack is an open source project licensed under the Apache License 2.0.

**Persistent volume**  - Changes to these types of disk volumes are saved.

**Public image** - An Image service VM image that is available to all projects.

**Public Key Authentication** - Authentication method that uses keys rather than passwords Backups.

**QCOW2 (QEMU copy-on-write version 2)** - One of the VM image disk formats supported by Image service.The QCOW image format is one of the disk image formats supported by the QEMU processor emulator. It is a representation of a fixed size block device in a file.

**RAW** - One of the VM image disk formats supported by Image service; an unstructured disk image. 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 dd command

**Routers** -  A physical or virtual network device that passes network traffic between

**Subnet** - Logical subdivision of an IP network.

**Security group** - A set of network traffic filtering rules that are applied to a Compute instance.

**Volumes** -  Disk-based data storage generally represented as an iSCSI target with a file system that supports extended attributes; can be persistent or ephemeral.

**XFS** - High-performance 64-bit file system created by Silicon Graphics. Excels in parallel I/O operations and data consistency.

**X509 Certificate** - is a standard format for public key certificates, digital documents that securely associate cryptographic key pairs with identities such as websites, individuals, or organizations.