Chelonia a lightweight self-healing distributed storage Zsombor Nagy - - PowerPoint PPT Presentation

Chelonia

a lightweight self-healing distributed storage Zsombor Nagy (zsombor@niif.hu) Salman Toor (salman.toor@it.uu.se) Jon Kerr Nilsen (j.k.nilsen@fys.uio.no)

Motivation

• How to easily...
• Create a storage resource from available disk

space on any computer

• Connect storage resources through the Internet
• Provide an easy-to-understand way for users to

upload and share their files

• Use these files in a Grid environment

Design

• The system should be...
• self-healing
• easy to deploy
• easy to maintain
• lightweight
• no single point of failure

Decisions

• Files
• Replication
• Berkeley DB HA
• HTTP(S) file transfer
• SOAP messaging
• X509 certificates

Chelonia

• Developed by the KnowARC project
• Will be maintained by the NorduGrid Collaboration
• Running in NorduGrid ARC’s web service container
• Written in Python
• Running on Linux and Mac OS X

(and Windows soon)

Grid Solution for Wide Area Computing and Data Handling Grid Solution for Wide Area Computing and Data Handling

NORDUGRID

The Chelonia Cloud

• Storage cloud for

anyone

• Can be created by

anyone

• Can be shared with

anyone

• Can be used by

anyone

Global namespace

• Global hierarchical

namespace

• Files are organized in

collections

• All users see the same

tree

• Can use logical names
• Paths in Chelonia

namespace

• Similar to paths in a

regular local filesystem

Replication

• Files are replicated
• User specifies how many

replicas are needed

• Chelonia itself takes care
• f the replication
• Easy to create a new

storage node

Access Control

• Access policies to files and

collections

• Can grant access to
• Individual users
• If in a Grid environment, to

entire virtual organizations

Client tools

• Several ways to access

Chelonia

• Command line interface
• FUSE module
• In an ARC enabled Grid

environment

• Through job

specification file

• With ARC client tools

FUSE module

• We have a FUSE module to

mount Chelonia as a local filesystem

• You can upload and

download files, create collections (directories) with your OS’s CLI and GUI tools (e.g. drag and drop)

• Linux and Mac OS X

Components of Chelonia

• Consists of four services
• The Bartender
• The Shepherd
• The Librarian
• The A-Hash
• Can have multiple

instances of all services

The Shepherd

• Manages the storage

node with the actual file data

• Replication requires

more storage nodes, each managed by a Shepherd

• Adding a Shepherd,

replica will automatically be created (if needed)

The Librarian and A-Hash

• The Librarian manages

the metadata

• Uses the A-Hash to

store the data

• Both metadata and

Librarians can be replicated

• More fault tolerant
• Better load balance

The Bartender

• Serves the users by

negotiating with

• the Librarian to query

files and collections

• the Shepherd to upload

and download files

• More than one Bartender to

eliminate single point of failure

• Users can contact any

Bartender and get the same result

Downloading

USER

1 . g e t F i l e ( L N )

• 2. traverse(LN)

3 . fi l e ' s m e t a d a t a 4 . g e t ( r e f e r e n c e I D )

• 6. TURL
• 7. downloading the file
• 5. TURL

L

S

B

A-H A-H A-H A-H

SES

Uploading

USER

1 . p u t F i l e ( L N )

• 2. traverse(LN)
• 3. parent's data

4 . n e w ( m e t a d a t a )

• 5. file's GUID

9 . p u t ( . . . ) 1 . r e g i s t e r n e w r e p l i c a

• 12. TURL

1 3 . u p l

• a

d i n g t h e fi l e

• 6. add entry to parent
• 11. TURL
• 14. report state change
• 8. list of Shepherds

SES

B

S

L

A-H A-H A-H A-H

Depth test

Width test

Multiple users

10 20 30 40 50 15 30 45 60 75 90 105 120 135 150 165

ALIVE OFFLINE THIRDWHEEL CREATING

10 20 30 40 50 15 30 45 60 75 90 105 120 135 150 165 180 195 210 225 10 20 30 40 50 15 30 45 60 75 90 105 120 135 105 165 180 195 210 225 240 255

User Side System Side

10 files of size 100MB have 3 replicas and now user:

• Increase the number replicas to 5.
• Decrease the number of replicas to 2

10 files with 4 replicas are in the system.

• One Shepherd went OFFLINE for sometime
• Became ONLINE

Number of files in the system Time in seconds taken by the system to achieve the needed replicas Number of files in the system Time in seconds taken by the system to achieve the needed replicas

Five Shepherds were used for this test

Number of replicas

Memory usage

8 days running with lots of file uploads and downloads

Future?

• Better clients?
• SRM? WebDAV?
• Encryption?
• AAI?
• Transfer protocols?
• Transfer security?
• Versioning?
• Resuming uploads?
• SOAP over HTTPS?
• Space reservation?

ClusterGrid

• Maintained by NIIF, Hungary
• Since 2002 connecting a few hundred PCs

located at several universities in Hungary

• Previously using NIIF’s own grid middleware
• Soon it will use ARC and Chelonia

Chelonia and ClusterGrid

• Soon there will be a purchase of some storage

solutions which will be deployed at chosen Hungarian universities

• We will deploy Chelonia storage nodes on these
• The ClusterGrid users will be able to
• upload and download (input/output) files to

the Chelonia cloud

• and refer to these files in the job descriptions

Questions / Demo

Thank You!

web: http://www.knowarc.eu/chelonia/ paper: http://arxiv.org/abs/1002.0712 video: http://www.youtube.com/watch?v=NEUWzGHHGhc Zsombor Nagy, NIIF (Hungary), zsombor@niif.hu