[arch-design] Minor edits to the compute design section
Minor IA and heading edits, remove duplication, and update links. Change-Id: I88ee48c883cf04272822d81bbd5ee1c568ebef20 Implements: blueprint arch-design-pike
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daz
Brian Moss
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@ -1,11 +1,11 @@
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=============
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Compute nodes
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=============
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===================
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Compute node design
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===================
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.. toctree::
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:maxdepth: 3
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design-compute/design-compute-concepts
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design-compute/design-compute-arch
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design-compute/design-compute-cpu
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design-compute/design-compute-hypervisor
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design-compute/design-compute-hardware
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@ -1,5 +1,5 @@
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====================================
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Compute Server Architecture Overview
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Compute server architecture overview
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====================================
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When designing compute resource pools, consider the number of processors,
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@ -7,11 +7,12 @@ amount of memory, network requirements, the quantity of storage required for
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each hypervisor, and any requirements for bare metal hosts provisioned
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through ironic.
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When architecting an OpenStack cloud, as part of the planning process, the
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architect must not only determine what hardware to utilize but whether compute
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When architecting an OpenStack cloud, as part of the planning process, you
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must not only determine what hardware to utilize but whether compute
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resources will be provided in a single pool or in multiple pools or
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availability zones. Will the cloud provide distinctly different profiles for
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compute?
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availability zones. You should consider if the cloud will provide distinctly
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different profiles for compute.
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For example, CPU, memory or local storage based compute nodes. For NFV
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or HPC based clouds, there may even be specific network configurations that
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should be reserved for those specific workloads on specific compute nodes. This
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@ -83,7 +84,7 @@ the hardware layout of your compute nodes.
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and cause a potential increase in a noisy neighbor.
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Insufficient disk capacity could also have a negative effect on overall
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performance including CPU and memory usage. Depending on the back-end
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performance including CPU and memory usage. Depending on the back end
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architecture of the OpenStack Block Storage layer, capacity includes
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adding disk shelves to enterprise storage systems or installing
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additional Block Storage nodes. Upgrading directly attached storage
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@ -1,3 +1,5 @@
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.. _choosing-a-cpu:
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==============
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Choosing a CPU
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==============
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@ -9,9 +11,10 @@ and *AMD-v* for AMD chips.
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.. tip::
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Consult the vendor documentation to check for virtualization support. For
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Intel, read `“Does my processor support Intel® Virtualization Technology?”
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<http://www.intel.com/support/processors/sb/cs-030729.htm>`_. For AMD, read
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`AMD Virtualization
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Intel CPUs, see
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`Does my processor support Intel® Virtualization Technology?
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<http://www.intel.com/support/processors/sb/cs-030729.htm>`_. For AMD CPUs,
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see `AMD Virtualization
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<http://www.amd.com/en-us/innovations/software-technologies/server-solution/virtualization>`_.
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Your CPU may support virtualization but it may be disabled. Consult your
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BIOS documentation for how to enable CPU features.
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@ -23,16 +26,17 @@ purchase a server that supports multiple CPUs, the number of cores is further
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multiplied.
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As of the Kilo release, key enhancements have been added to the
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OpenStack code to improve guest performance. These improvements allow OpenStack
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nova to take advantage of greater insight into a Compute host's physical layout
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and therefore make smarter decisions regarding workload placement.
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Administrators can use this functionality to enable smarter planning choices
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for use cases like NFV (Network Function Virtualization) and HPC (High
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OpenStack code to improve guest performance. These improvements allow the
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Compute service to take advantage of greater insight into a compute host's
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physical layout and therefore make smarter decisions regarding workload
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placement. Administrators can use this functionality to enable smarter planning
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choices for use cases like NFV (Network Function Virtualization) and HPC (High
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Performance Computing).
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Considering NUMA is important when selecting CPU sizes and types, there are use
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cases that use NUMA pinning to reserve host cores for OS processes. These
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reduce the available CPU for workloads and protects the OS.
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Considering non-uniform memory access (NUMA) is important when selecting CPU
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sizes and types, as there are use cases that use NUMA pinning to reserve host
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cores for operating system processes. These reduce the available CPU for
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workloads and protects the operating system.
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.. tip::
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@ -55,11 +59,12 @@ reduce the available CPU for workloads and protects the OS.
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Additionally, CPU selection may not be one-size-fits-all across enterprises,
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but more of a list of SKUs that are tuned for the enterprise workloads.
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A deeper discussion about NUMA can be found in `CPU topologies in the Admin
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Guide <https://docs.openstack.org/admin-guide/compute-cpu-topologies.html>`_.
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For more information about NUMA, see `CPU topologies
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<https://docs.openstack.org/admin-guide/compute-cpu-topologies.html>`_ in
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the Administrator Guide.
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In order to take advantage of these new enhancements in OpenStack nova, Compute
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hosts must be using NUMA capable CPUs.
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In order to take advantage of these new enhancements in the Compute service,
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compute hosts must be using NUMA capable CPUs.
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.. tip::
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@ -1,8 +1,8 @@
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=========================
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========================
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Choosing server hardware
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=========================
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========================
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Consider the following factors when selecting compute (server) hardware:
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Consider the following factors when selecting compute server hardware:
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* Server density
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A measure of how many servers can fit into a given measure of
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@ -20,10 +20,6 @@ Consider the following factors when selecting compute (server) hardware:
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The relative cost of the hardware weighed against the total amount of
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capacity available on the hardware based on predetermined requirements.
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Compute (server) hardware selection
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Weigh these considerations against each other to determine the best design for
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the desired purpose. For example, increasing server density means sacrificing
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resource capacity or expandability. It also can decrease availability and
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@ -32,103 +28,36 @@ expandability can increase cost but decrease server density. Decreasing cost
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often means decreasing supportability, availability, server density, resource
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capacity, and expandability.
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The primary job of the OpenStack architect is to determine the requirements for
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the cloud prior to constructing the cloud, and planning for expansion
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and new features that may require different hardware. Planning for hardware
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lifecycles is also the job of the architect. However, if the cloud is initially
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built with near end of life, but cost effective hardware, then the
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performance and capacity demand of new workloads will drive the purchase of
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more modern hardware quicker. With individual harware components changing over
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time, companies may prefer to manage configurations as stock keeping units
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(SKU)s. This method provides an enterprise with a standard configuration unit
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of compute (server) that can be placed in any IT service manager or vendor
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supplied ordering system that can be triggered manually or through advanced
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operational automations. This simplifies ordering, provisioning, and
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activating additional compute resources. For example, there are plug-ins for
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several commercial service management tools that enable integration with
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hardware APIs. This configures and activates new compute resources from standby
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hardware based on a standard configurations. Using this methodology, spare
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hardware can be ordered for a datacenter and provisioned based on
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capacity data derived from OpenStack Telemetry.
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Determine the requirements for the cloud prior to constructing the cloud,
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and plan for hardware lifecycles, and expansion and new features that may
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require different hardware.
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If the cloud is initially built with near end of life, but cost effective
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hardware, then the performance and capacity demand of new workloads will drive
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the purchase of more modern hardware. With individual hardware components
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changing over time, you may prefer to manage configurations as stock keeping
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units (SKU)s. This method provides an enterprise with a standard
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configuration unit of compute (server) that can be placed in any IT service
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manager or vendor supplied ordering system that can be triggered manually or
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through advanced operational automations. This simplifies ordering,
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provisioning, and activating additional compute resources. For example, there
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are plug-ins for several commercial service management tools that enable
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integration with hardware APIs. These configure and activate new compute
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resources from standby hardware based on a standard configurations. Using this
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methodology, spare hardware can be ordered for a datacenter and provisioned
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based on capacity data derived from OpenStack Telemetry.
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Compute capacity (CPU cores and RAM capacity) is a secondary consideration for
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selecting server hardware. The required server hardware must supply adequate
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CPU sockets, additional CPU cores, and adequate RAM, and is discussed in detail
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under the CPU selection secution.
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CPU sockets, additional CPU cores, and adequate RA. For more information, see
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:ref:`choosing-a-cpu`.
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However, there are also network and storage considerations for any compute
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server. Network considerations are discussed in the
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`network section
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<https://docs.openstack.org/draft/arch-design-draft/design-networking.html>`_
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of this chapter.
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In compute server architecture design, you must also consider network and
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storage requirements. For more information on network considerations, see
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:ref:`network-design`.
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Scaling your cloud
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~~~~~~~~~~~~~~~~~~
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For a compute-focused cloud, emphasis should be on server
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hardware that can offer more CPU sockets, more CPU cores, and more RAM.
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Network connectivity and storage capacity are less critical.
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When designing a OpenStack cloud compute server architecture, you must
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consider whether you intend to scale up or scale out. Selecting a
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smaller number of larger hosts, or a larger number of smaller hosts,
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depends on a combination of factors: cost, power, cooling, physical rack
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and floor space, support-warranty, and manageability. Typically, the scale out
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model has been popular for OpenStack because it further reduces the number of
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possible failure domains by spreading workloads across more infrastructure.
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However, the downside is the cost of additional servers and the datacenter
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resources needed to power, network, and cool them.
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Hardware selection considerations
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Consider the following in selecting server hardware form factor suited for
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your OpenStack design architecture:
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* Most blade servers can support dual-socket multi-core CPUs. To avoid
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this CPU limit, select ``full width`` or ``full height`` blades. Be
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aware, however, that this also decreases server density. For example,
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high density blade servers such as HP BladeSystem or Dell PowerEdge
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M1000e support up to 16 servers in only ten rack units. Using
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half-height blades is twice as dense as using full-height blades,
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which results in only eight servers per ten rack units.
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* 1U rack-mounted servers have the ability to offer greater server density
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than a blade server solution, but are often limited to dual-socket,
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multi-core CPU configurations. It is possible to place forty 1U servers
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in a rack, providing space for the top of rack (ToR) switches, compared
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to 32 full width blade servers.
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To obtain greater than dual-socket support in a 1U rack-mount form
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factor, customers need to buy their systems from Original Design
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Manufacturers (ODMs) or second-tier manufacturers.
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.. warning::
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This may cause issues for organizations that have preferred
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vendor policies or concerns with support and hardware warranties
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of non-tier 1 vendors.
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* 2U rack-mounted servers provide quad-socket, multi-core CPU support,
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but with a corresponding decrease in server density (half the density
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that 1U rack-mounted servers offer).
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* Larger rack-mounted servers, such as 4U servers, often provide even
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greater CPU capacity, commonly supporting four or even eight CPU
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sockets. These servers have greater expandability, but such servers
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have much lower server density and are often more expensive.
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* ``Sled servers`` are rack-mounted servers that support multiple
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independent servers in a single 2U or 3U enclosure. These deliver
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higher density as compared to typical 1U or 2U rack-mounted servers.
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For example, many sled servers offer four independent dual-socket
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nodes in 2U for a total of eight CPU sockets in 2U.
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Other factors to consider
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~~~~~~~~~~~~~~~~~~~~~~~~~
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Considerations when choosing hardware
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Here are some other factors to consider when selecting hardware for your
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compute servers.
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@ -158,27 +87,27 @@ cooling. The number of hosts (or hypervisors) that can be fitted
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into a given metric (rack, rack unit, or floor tile) is another
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important method of sizing. Floor weight is an often overlooked
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consideration.
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The data center floor must be able to support the
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weight of the proposed number of hosts within a rack or set of
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racks. These factors need to be applied as part of the host density
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calculation and server hardware selection.
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The data center floor must be able to support the weight of the proposed number
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of hosts within a rack or set of racks. These factors need to be applied as
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part of the host density calculation and server hardware selection.
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Power and cooling density
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-------------------------
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The power and cooling density requirements might be lower than with
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blade,sled, or 1U server designs due to lower host density (by
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blade, sled, or 1U server designs due to lower host density (by
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using 2U, 3U or even 4U server designs). For data centers with older
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infrastructure, this might be a desirable feature.
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Data centers have a specified amount of power fed to a given rack or
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set of racks. Older data centers may have a power density as power
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as low as 20 AMPs per rack, while more recent data centers can be
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architected to support power densities as high as 120 AMP per rack.
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The selected server hardware must take power density into account.
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set of racks. Older data centers may have power densities as low as 20A per
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rack, and current data centers can be designed to support power densities as
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high as 120A per rack. The selected server hardware must take power density
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into account.
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Specific hardware concepts
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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Selecting hardware form factor
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Consider the following in selecting server hardware form factor suited for
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your OpenStack design architecture:
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@ -221,3 +150,16 @@ your OpenStack design architecture:
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higher density as compared to typical 1U or 2U rack-mounted servers.
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For example, many sled servers offer four independent dual-socket
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nodes in 2U for a total of eight CPU sockets in 2U.
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Scaling your cloud
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~~~~~~~~~~~~~~~~~~
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When designing a OpenStack cloud compute server architecture, you must
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decide whether you intend to scale up or scale out. Selecting a
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smaller number of larger hosts, or a larger number of smaller hosts,
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depends on a combination of factors: cost, power, cooling, physical rack
|
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and floor space, support-warranty, and manageability. Typically, the scale out
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model has been popular for OpenStack because it reduces the number of possible
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failure domains by spreading workloads across more infrastructure.
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However, the downside is the cost of additional servers and the datacenter
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resources needed to power, network, and cool the servers.
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@ -21,22 +21,20 @@ parity, documentation, and the level of community experience.
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As per the recent OpenStack user survey, KVM is the most widely adopted
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hypervisor in the OpenStack community. Besides KVM, there are many deployments
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that run other hypervisors such as LXC, VMware, Xen and Hyper-V. However, these
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hypervisors are either less used, are niche hypervisors, or have limited
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functionality based on the more commonly used hypervisors. This is due to gaps
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in feature parity.
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In addition, the nova configuration reference below details feature support for
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hypervisors as well as ironic and Virtuozzo (formerly Parallels).
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The best information available to support your choice is found on the
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`Hypervisor Support Matrix
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<https://docs.openstack.org/developer/nova/support-matrix.html>`_
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and in the `configuration reference
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<https://docs.openstack.org/ocata/config-reference/compute/hypervisors.html>`_.
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that run other hypervisors such as LXC, VMware, Xen, and Hyper-V. However,
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these hypervisors are either less used, are niche hypervisors, or have limited
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functionality compared to more commonly used hypervisors.
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.. note::
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It is also possible to run multiple hypervisors in a single
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deployment using host aggregates or cells. However, an individual
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compute node can run only a single hypervisor at a time.
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For more information about feature support for
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hypervisors as well as ironic and Virtuozzo (formerly Parallels), see
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`Hypervisor Support Matrix
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<https://docs.openstack.org/developer/nova/support-matrix.html>`_
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and `Hypervisors
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<https://docs.openstack.org/ocata/config-reference/compute/hypervisors.html>`_
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in the Configuration Reference.
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@ -5,12 +5,13 @@ Compute server logging
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The logs on the compute nodes, or any server running nova-compute (for example
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in a hyperconverged architecture), are the primary points for troubleshooting
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issues with the hypervisor and compute services. Additionally, operating system
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logs can also provide useful information. However, as environments grow, the
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amount of log data increases exponentially. Enabling debugging on either the
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OpenStack services or the operating system logging further compounds the data
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issues.
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logs can also provide useful information.
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Logging is detailed more fully in the `Operations Guide
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As the cloud environment grows, the amount of log data increases exponentially.
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Enabling debugging on either the OpenStack services or the operating system
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further compounds the data issues.
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Logging is described in more detail in the `Operations Guide
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<http://docs.openstack.org/ops-guide/ops-logging-monitoring.html>`_. However,
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it is an important design consideration to take into account before commencing
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operations of your cloud.
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@ -18,7 +19,7 @@ operations of your cloud.
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OpenStack produces a great deal of useful logging information, but for
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the information to be useful for operations purposes, you should consider
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having a central logging server to send logs to, and a log parsing/analysis
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system (such as Elastic Stack [formerly known as ELK]).
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system such as Elastic Stack [formerly known as ELK].
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Elastic Stack consists of mainly three components: Elasticsearch (log search
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and analysis), Logstash (log intake, processing and output) and Kibana (log
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@ -35,28 +36,28 @@ Redis and Memcached. In newer versions of Elastic Stack, a file buffer called
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similar purpose but adds a "backpressure-sensitive" protocol when sending data
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to Logstash or Elasticsearch.
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Many times, log analysis requires disparate logs of differing formats, Elastic
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Stack (namely logstash) was created to take many different log inputs and then
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transform them into a consistent format that elasticsearch can catalog and
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Log analysis often requires disparate logs of differing formats. Elastic
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Stack (namely Logstash) was created to take many different log inputs and
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transform them into a consistent format that Elasticsearch can catalog and
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analyze. As seen in the image above, the process of ingestion starts on the
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servers by logstash, is forwarded to the elasticsearch server for storage and
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searching and then displayed via Kibana for visual analysis and interaction.
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servers by Logstash, is forwarded to the Elasticsearch server for storage and
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searching, and then displayed through Kibana for visual analysis and
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interaction.
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For instructions on installing Logstash, Elasticsearch and Kibana see `the
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elastic stack documentation.
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For instructions on installing Logstash, Elasticsearch and Kibana, see the
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`Elasticsearch reference
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<https://www.elastic.co/guide/en/elasticsearch/reference/current/getting-started.html>`_.
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There are some specific configuration parameters that are needed to
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configure logstash for OpenStack. For example, in order to get logstash to
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collect, parse and send the correct portions of log files and send them to the
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elasticsearch server, you need to format the configuration file properly. There
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are input, output and filter configurations. Input configurations tell logstash
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who and what to recieve data from (log files/
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forwarders/filebeats/StdIn/Eventlog/etc.), output specifies where to put the
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data, and filter configurations define the input contents to forward to the
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output.
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configure Logstash for OpenStack. For example, in order to get Logstash to
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collect, parse, and send the correct portions of log files to the Elasticsearch
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server, you need to format the configuration file properly. There
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are input, output and filter configurations. Input configurations tell Logstash
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where to recieve data from (log files/forwarders/filebeats/StdIn/Eventlog),
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output configurations specify where to put the data, and filter configurations
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define the input contents to forward to the output.
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The logstash filter performs intermediary processing on each event. Conditional
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The Logstash filter performs intermediary processing on each event. Conditional
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filters are applied based on the characteristics of the input and the event.
|
||||
Some examples of filtering are:
|
||||
|
||||
@ -88,16 +89,15 @@ representation of events such as:
|
||||
|
||||
These input, output and filter configurations are typically stored in
|
||||
:file:`/etc/logstash/conf.d` but may vary by linux distribution. Separate
|
||||
configuration files should be created for different logging systems(syslog,
|
||||
apache, OpenStack, etc.)
|
||||
configuration files should be created for different logging systems such as
|
||||
syslog, Apache, and OpenStack.
|
||||
|
||||
General examples and configuration guides can be found on the Elastic `Logstash
|
||||
Configuration page
|
||||
<https://www.elastic.co/guide/en/logstash/current/configuration-file-structure.html>`_
|
||||
<https://www.elastic.co/guide/en/logstash/current/configuration-file-structure.html>`_.
|
||||
|
||||
OpenStack input, output and filter examples can be found at
|
||||
`https://github.com/sorantis/elkstack/tree/master/elk/logstash
|
||||
<https://github.com/sorantis/elkstack/tree/master/elk/logstash>`_
|
||||
https://github.com/sorantis/elkstack/tree/master/elk/logstash.
|
||||
|
||||
Once a configuration is complete, Kibana can be used as a visualization tool
|
||||
for OpenStack and system logging. This will allow operators to configure custom
|
||||
|
||||
@ -1,6 +1,6 @@
|
||||
=====================
|
||||
====================
|
||||
Network connectivity
|
||||
=====================
|
||||
====================
|
||||
|
||||
The selected server hardware must have the appropriate number of network
|
||||
connections, as well as the right type of network connections, in order to
|
||||
|
||||
@ -1,11 +1,11 @@
|
||||
==============
|
||||
Overcommitting
|
||||
==============
|
||||
==========================
|
||||
Overcommitting CPU and RAM
|
||||
==========================
|
||||
|
||||
OpenStack allows you to overcommit CPU and RAM on compute nodes. This
|
||||
allows you to increase the number of instances you can have running on
|
||||
your cloud, at the cost of reducing the performance of the instances.
|
||||
OpenStack Compute uses the following ratios by default:
|
||||
allows you to increase the number of instances running on your cloud at the
|
||||
cost of reducing the performance of the instances. The Compute service uses the
|
||||
following ratios by default:
|
||||
|
||||
* CPU allocation ratio: 16:1
|
||||
* RAM allocation ratio: 1.5:1
|
||||
@ -20,13 +20,13 @@ The formula for the number of virtual instances on a compute node is
|
||||
``(OR*PC)/VC``, where:
|
||||
|
||||
OR
|
||||
CPU overcommit ratio (virtual cores per physical core)
|
||||
CPU overcommit ratio (virtual cores per physical core)
|
||||
|
||||
PC
|
||||
Number of physical cores
|
||||
Number of physical cores
|
||||
|
||||
VC
|
||||
Number of virtual cores per instance
|
||||
Number of virtual cores per instance
|
||||
|
||||
Similarly, the default RAM allocation ratio of 1.5:1 means that the
|
||||
scheduler allocates instances to a physical node as long as the total
|
||||
@ -39,6 +39,7 @@ with the instances reaches 72 GB (such as nine instances, in the case
|
||||
where each instance has 8 GB of RAM).
|
||||
|
||||
.. note::
|
||||
|
||||
Regardless of the overcommit ratio, an instance can not be placed
|
||||
on any physical node with fewer raw (pre-overcommit) resources than
|
||||
the instance flavor requires.
|
||||
|
||||
@ -2,7 +2,7 @@
|
||||
Instance storage solutions
|
||||
==========================
|
||||
|
||||
As part of the architecture design for a compute cluster, you must specify some
|
||||
As part of the architecture design for a compute cluster, you must specify
|
||||
storage for the disk on which the instantiated instance runs. There are three
|
||||
main approaches to providing temporary storage:
|
||||
|
||||
@ -122,7 +122,7 @@ from one physical host to another, a necessity for performing upgrades
|
||||
that require reboots of the compute hosts, but only works well with
|
||||
shared storage.
|
||||
|
||||
Live migration can also be done with nonshared storage, using a feature
|
||||
Live migration can also be done with non-shared storage, using a feature
|
||||
known as *KVM live block migration*. While an earlier implementation of
|
||||
block-based migration in KVM and QEMU was considered unreliable, there
|
||||
is a newer, more reliable implementation of block-based live migration
|
||||
|
||||
@ -1,8 +1,8 @@
|
||||
.. _network-design:
|
||||
|
||||
==============
|
||||
Network design
|
||||
==============
|
||||
==========
|
||||
Networking
|
||||
==========
|
||||
|
||||
.. toctree::
|
||||
:maxdepth: 2
|
||||
|
||||
Loading…
Reference in New Issue
Block a user