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OMI - Infrastructure Delivery and Logistics > Openstack Scaling and Capacity Planning > Flashcards

Openstack Scaling and Capacity Planning Flashcards

1
Q

What is the primary scaling approach used by OpenStack?

A

Horizontal scaling - adding more servers with identical configurations rather than upgrading to larger servers

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2
Q

What determines hardware failure likelihood in servers?

A

The chance of failure is highest at the start and end of its life cycle

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3
Q

What is the default CPU overcommit ratio in nova.conf?

A

0.6673611111111111

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4
Q

What are the four methods to segregate an OpenStack cloud?

A

Cells,
regions,
availability zones,
and
host aggregates

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5
Q

How does the OpenStack dashboard currently handle regions?

A

It uses only a single region, so one dashboard service should be run per region

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6
Q

What should be considered when estimating API service load?

A

Usage patterns,
user access patterns
VM lifetime,
and frequency of VM creation/termination,

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7
Q

What are the key considerations for hardware procurement in OpenStack?

A

Hardware should be stable, supported by OpenStack-compatible Linux distribution, and have the same CPU type to support instance migration

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8
Q

What is the purpose of burn-in testing?

A

Testing that stresses hardware to its limits to trigger early-stage failures, typically done through CPU or disk benchmarks over several days

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9
Q

How can you determine the scalability needs of your cloud?

A

By tracking metrics like
core count,
VM expectations,
storage requirements,
and applying ratios based on flavor templates

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10
Q

What are the default OpenStack flavors?

A

m1.tiny (1 core, 512MB RAM), m1.small (1 core, 2GB RAM), m1.medium (2 cores, 4GB RAM), m1.large (4 cores, 8GB RAM), m1.xlarge (8 cores, 16GB RAM)

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11
Q

What is the typical core capacity of a basic cloud controller server?

A

An eight core, 8GB RAM server typically handles up to a rack of compute nodes

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12
Q

What must be considered when horizontally scaling user-facing services?

A

They should be
load balanced using standard HTTP methods like
DNS round robin,
hardware load balancer, or
software like Pound or HAProxy

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13
Q

What special consideration must be made when load balancing the dashboard’s VNC proxy?

A

The VNC proxy uses
WebSocket protocol
which can be challenging for
L7 load balancers to handle

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14
Q

How can you calculate the expected number of VMs your cloud can support?
(Equation)

A

(overcommit fraction × cores) / virtual cores per instance

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15
Q

What role does nova-cells play in a cell-based deployment?

A

It manages the communication between the API cell and child cells

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16
Q

What are the shared services between all availability zones?

A

Keystone and all nova services

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17
Q

What metric should be considered when adding object storage nodes?

A

A weight should be specified that reflects the capability of the node

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18
Q

How does nova-scheduler handle compute nodes with different specifications?

A

It automatically handles differences in core count and RAM amounts

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19
Q

What is the main purpose of the API cell in a cells deployment?

A

It runs the nova-api service but no nova-compute services

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20
Q

What services can be configured to use multiple processes?

A

nova-api and glance-api through a flag in their configuration files

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21
Q

What types of separation does a region provide?

A

Discrete separation with separate API endpoints and no coordination between regions

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22
Q

How are availability zones defined in OpenStack?

A

They are defined locally on each server to identify the zone in which a specified compute host resides

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23
Q

What is a common use case for host aggregates?

A

To provide information for use with the nova-scheduler, such as grouping hosts that share specific flavors or images

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24
Q

What impact does leaving the OpenStack dashboard instances tab open have?

A

It refreshes the list of VMs every 30 seconds, potentially increasing load significantly

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25
Q

How should you handle service availability in a scaled cloud?

A

User-facing services should be load balanced using standard HTTP load-balancing methods

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26
Q

What is unique about the API cell’s configuration?

A

It’s the only cell that runs nova-api but doesn’t run nova-compute services

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27
Q

How are resource weights handled in object storage nodes?

A

A weight should be specified to reflect each node’s capability when adding new storage nodes

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28
Q

What is the recommended setup for dashboard services across regions?

A

Run one dashboard service per region since it only uses a single region

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29
Q

What determines the processing power needed for cloud controller cores?

A

User access patterns, VM creation frequency, and average VM lifetime

30
Q

How does instance listing affect cloud controller load?

A

Frequent instance listing operations can significantly increase load on nova-api and its database

31
Q

What is the purpose of burn-in testing duration?

A

To run long enough (several days) to trigger potential early-stage hardware failures

32
Q

How should metadata keys be handled in host aggregates?

A

They should be set consistently and matched with instance type extra specs

33
Q

What is the relationship between cells in a deployment?

A

Cells are configured in a tree structure with an API cell at the top level

34
Q

How does OpenStack handle hardware diversity in compute nodes?

A

nova-scheduler manages differences in core count and RAM, but CPU speeds affect performance

35
Q

What should be considered when planning cloud controller capacity?

A

API service load, database server load, and queue server load based on usage patterns

36
Q

What is the recommended approach for scaling OpenStack services?

A

Horizontal scaling with identically configured services that communicate via message bus

37
Q

Why is hardware stability important in a cloud environment?

A

To provide a stable foundation for hosting volatile cloud resources and services

38
Q

What is the Configuration option that was deprecated regarding availability zones?

A

CONF.node_availability_zone was deprecated but still works

39
Q

What is the recommended hardware type for OpenStack deployment?

A

Standard value-for-money offerings that most hardware vendors stock

40
Q

How can you verify capacity requirements for cloud expansion?

A

By monitoring metrics detailed in Chapter 13, Logging and Monitoring

41
Q

What types of benchmark tests are recommended for burn-in testing?

A

CPU and disk benchmarks run over several days

42
Q

What is the main consideration when configuring services like nova-api for multiple processes?

A

Changes must be made through flags in their configuration files to enable work sharing between cores

43
Q

How does the euca-describe-availability-zones command differ in verbose mode?

A

Verbose mode shows internal availability zones while non-verbose mode hides them

44
Q

What happens to the internal availability zone in availability zone listings?

A

It’s hidden in non-verbose euca-describe-availability_zones output

45
Q

What is considered experimental in OpenStack’s segregation methods?

A

The cells feature is considered experimental

46
Q

What is the key difference in managing child cells vs. the API cell?

A

Child cells run all typical nova services except nova-api, while API cell runs only nova-api

47
Q

What are the components needed in a child cell deployment?

A

All typical nova-* services except nova-api, plus its own message queue and database service

48
Q

How can you calculate the storage requirements for your cloud?

A

Multiply the flavor disk size by the number of expected instances

49
Q

What is Table 5.2’s recommended use case for cells?

A

When you need a single API endpoint for compute or require a second level of scheduling

50
Q

What services are shared between child cells and the API cell?

A

Only Keystone and nova-api

51
Q

What considerations should be made for database loading in a scaled deployment?

A

MySQL load balancing options should be configured, and AMQP brokers should use built-in clustering support

52
Q

What is the primary difference between segregating with cells/regions versus availability zones/host aggregates?

A

Cells and regions segregate entire cloud deployments, while availability zones and host aggregates divide a single Compute deployment

53
Q

What is the AggregateInstanceExtraSpecsFilter used for?

A

To ensure instances are scheduled only on hosts in aggregates that define the same key to the same value

54
Q

What are the two filters that use allocation ratio values in host aggregates?

A

AggregateCoreFilter and AggregateRamFilter

55
Q

What is the recommended way to handle allocation ratios across multiple aggregates?

A

Each host should have only one allocation ratio for each resource, even when in multiple aggregates

56
Q

What was changed regarding availability zones for services like nova-scheduler and nova-network?

A

These services now span all availability zones instead of having their own

57
Q

What is CONF.internal_service_availability_zone used for?

A

It’s used when running operations like nova host-list, euca-describe-availability-zones verbose, and nova-manage service list

58
Q

What happened to CONF.node_availability_zone?

A

It was renamed to CONF.default_availability_zone and is now only used by nova-api and nova-scheduler services

59
Q

How should high-intensity and low-intensity computing loads be handled in the same cloud?

A

By setting different CPU and RAM allocation ratios through aggregate metadata and instance type extra specs

60
Q

What is the recommended abstraction method for allocation ratios?

A

Define an additional key-value pair like ‘overcommit’ with values ‘high,’ ‘medium,’ or ‘low’ rather than matching directly on allocation ratios

61
Q

What parameters should be monitored for key hardware specifications?

A

Storage performance (spindles/core), memory availability (RAM/core), network bandwidth (Gbps/core), and CPU performance (CPU/core)

62
Q

What types of separation can availability zones provide?

A

Physical isolation, redundancy, power supply separation, and network equipment separation

63
Q

How should compute nodes be added to an existing installation?

A

They can be simply added and will be automatically picked up by the existing installation

64
Q

What determines if a service can be installed on a new server for expansion?

A

Services that communicate only using the message queue internally can be easily added to new servers

65
Q

What is the advantage of using regions for site separation?

A

They allow for discrete separation with separate API endpoints while maintaining shared infrastructure

66
Q

What is the primary concern when having a host in multiple aggregates?

A

Avoiding conflicting allocation ratio values for the same resource across different aggregates

67
Q

What are the key metrics to monitor for cloud growth?

A

Resource usage and user growth patterns to determine when to procure additional resources

68
Q

What is the benefit of using non-identical hardware in OpenStack?

A

New nodes don’t need to be the same specification or vendor as existing nodes, providing flexibility in scaling

69
Q

How does nova-scheduler handle CPU differences in compute nodes?

A

It handles core count and RAM differences, but CPU speed differences will affect user experience

70
Q

What is the significance of WebSocket protocol in dashboard deployment?

A

It’s used by the VNC proxy and can cause challenges with L7 load balancers

71
Q

What are the three main building blocks for hardware procurement?

A

Compute, object storage, and cloud controller

72
Q

What factors affect cloud controller core requirements?

A

User patterns, VM creation frequency, and typical VM lifetime

OMI - Infrastructure Delivery and Logistics (2 decks)

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