Friday 24 June 2016

OpenStack Interview Questions and Answers

Friends, here are the some interview questions with answers on OpenStack.

What is OpenStack?

OpenStack is a package of software tools for controlling storage, compute, hypervisors and networking resource in a datacenter. Basically its a software tool for managing IAAS (Infrastructure as a Service) cloud. These days more and more datacenter is migrating to manage its resource on OpenStack.

What are the different OpenStack Services or components?
Keystone: Component that provides mechanism for user authentication.
Glance: Maintains & manages images in different format
Cinder: Provides Persistent block storage
Neutron: Its provides interface to the networks so that you can access network resources (or you can say "Network as a service").
Nova: On user demand, provides instances
Swift: It is a storage platform which can be united into application
Ceilometer: It provides metering of core components which is used for billing purpose. You have datacenter customers and you want to bill them for its usage.
Heat: Offer automated infrastructure deployment
Guava: UI component for OpenStack for administrators

Name some hypervisors which OpenStack supports?
(a) Vmware
(b) Xen
(c) KVM
(d) HyperV

What are the modular architectural components of OpenStack?
OpenStack Compute: It maintains huge networks of virtual machines and hypervisors
OpenStack Object Storage: Its a storage system which manages and provides support for object and block storage
Image Service:  This components provides provides discovery and registration for virtual disk images

What are the types of storage provided by OpenStack Compute?
(a) Persistent or Volume Storage
(b) Ephemeral Storage

What is the use of user, role and tenant?
User - member of different projects
tenant - group of users
role - specifies authorization level of the user

What is identity service in openstack?
Openstack identity service is managed by Keystone. Its service is primarily responsibile for:
User Management - Its tracks users alongwith its permission
Service Catalog - As name indicates, it provides catalog for the available service with their api

How to pause and unpause/resume an instance?
To pause an instance - nova pause INSTANCE_NAME
To resume/unpause - nova unpause INSTANCE_NAME

What is the command to create a container?
$ swift post CONTAINER_NAME

What is the command to list and check the status of containers?
To list containers - $ swift list
To check status - $ swift stat CONTAINER_NAME

What are the networking options used in OpenStack?
Flat Network Manager - It doesnt configure ip of the instance and left to system administrator to assign an ip.
Flat DHCP Network Manager - Its ip is fetched from the subnet.
VLAN Network Manager - Creates a Vlan interface and on each vlan, DHCP server is started to fetch ip for the instances.

What is cells in OpenStack?
Cells functionality enables you to scale up an OpenStack Compute cloud. It supports very large deployment. Here is how its works - the hosts in an OpenStack Compute cloud are partitioned multiple cells/groups, which is configured as a tree.

How to create user, tenant and roles in OpenStack?
$ keystone user-create --name USERNAME --pass PASSWORD --email EMAIL_ADDRESS
$ keystone tenant-create --name USERNAME --description "BLA BLA BLA"
$ keystone role-create --name USERNAME

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