openstack storage overview

OpenStack Storage Overview

Feb 2015

Bharat Kumar Kobagana

OpenStack

Gnunify OpenStack Mini Conference 2015

Ephemeral Storage

● Disappear when a virtual machine is terminated

● Comes with OpenStack Compute Service (Nova)

Persistent Storage

● Always available, regardless of the status of virtual machine

● OpenStack support two types of persistent storage

● Object Storage

● Block Storage

● Shared Filesystem as Service

Introduction to OpenStack Storage


Introduction to OpenStack Storage Cont…


BLOCK FILE OBJECT

Low level I/O

Tracks & Sectors

No metadata

SCSI, SATA, ATA

SAN

Directories & Files

NFS, Local FS

Simplicity

NAS

Rigid Metadata

Containers / Buckets

Data, Metadata &

Identifier

HTTP

Abstracted

Cinder Manila Swift

?

What is Cinder

Swift Overview

Cinder Components

Cinder Architecture

Cinder Features

Backend Drivers

GlusterFS as a Backend

What’s next?

Agenda


Swift is a highly available, distributed, eventually consistent object store.

Object is {Data + Metadata + Identifier}

Alternative to Amazon S3

Decoupled / Independent from OpenStack

Unstructured data

Scales horizontally

But you can’t..

Mount it

Have file hierarchies

Swift


Hierarchy and Namespace

Account -> Containers -> Objectsc

Swift Cntd…


Internal data structures stored in “ring files” in /etc/swift

Maps objects to physical location on disk

Uses hashing to place objects just like GlusterFS :)

Eliminates need for central meta-data server

Needs to be recreated when cluster layout changes

Rings


Swift Cntd…


GET'X-Auth-Token: blah_blah'

http://example.com:8080/v1/AUTH_test/c1/a/b/c.jpg

Proxy server

Account

ContainerObject

Request

method Request

header

All operations are carried out by sending HTTP requests.

Each object’s access path consists of exactly three elements:

/account/container/object

Code name for OpenStack Block Storage / Volume Storage

Spun off from Nova

Cinder volumes (block devices) are attached to VMs

Volume lifecycle is independent of virtual machine instances

Backend devices opaque to users

Consistent API regardless of backend selection

Similar to Amazon EBS

Users interact with block storage by attaching volumes their VMs

Cinder provides APIs such as create / delete volume, backup / restore

volume, snapshot / clone volume and many more.

What is Cinder


cinder-api

● Accepts API requests

● Routes the requests to the cinder-volume for action

cinder-scheduler

● Selects one of the nodes to create volume

● Similar to nova-scheduler

cinder-volume

● Interacts directly with Block Storage

● Responds to read and write requests sent to the Block Storage

Cinder Components


Cinder Architecture


Web Dashboard

Cinder client

Nova client

api

AuthManager

REST

AMQP Scheduler

Volume

Volume

Volume

iSCSI

iSCSI

iSCSI

Cinder Architecture


Cinder Client

cinder-api

cinder-volume cinder-scheduler cinder-backup

Cinder DBAMQP

AMQP

Basic Features

● Attach volume to instance

● Create bootable volume / Create volume from image

● Upload volume to Glance

● Snapshot a volume

● Create volume from snapshot

Cinder Features


Cinder – Nova communication


Nova

VM Instance

KVM Storage Controller

iSCSItarget

/dev/vda

Cinder

iSCSIinitiator

iSCSI is just an example – several

other protocols are also supported

(e.g., FC, NFS)

Persistent Volume Control Persistent Volume Data

Volume Replication

Consistency Groups

Support for Volume Pools

Volume Multi Attach

Manage / Unmanage Volumes

Backup Volumes

Volume retype

What Next


Backend is a storage system which implements the APIs provided by

Cinder.

Backend typically exports a storage pool which is used by Cinder to

provision new storage (aka cinder volumes)

Some of those are:

● LVM (Logical Volume Manager)

● Ceph

● GlusterFS

By default Cinder uses LVM as its backend.

Backend is configured in Cinder via the cinder.conf file.

To get list of all backends:

https://wiki.openstack.org/wiki/CinderSupportMatrix

Backend Drivers


Available in upstream.

1 Cinder Volume = 1 file in Gluster volume

Support raw and qcow2 format Cinder volumes

GlusterFS backend Cinder volumes can be attached to Nova instance

in two ways:

● FUSE mount

● Libgfapi

Supports most of the Cinder APIs including multi-backend feature.

GlusterFS as a Cinder Backend


Storage Backend

GlusterFS as a Cinder Backend cont…


Cinder Client

cinder-api

cinder-volume cinder-scheduler cinder-backup

Cinder DBAMQP

AMQP

GlusterFS

Queries?


Thank You Very Much…!


openstack storage overview

Engineering