obligatory rubric - storage networking industry association · pdf file(dbms) file system (fs)...

1 Copyright © 2000,2003, Storage Networking Industry Association

Obligatory rubric

• Copyright © 2000,2003 Storage Networking Industry Association (SNIA).

• SNIA-TC members may use this material freely; all others require permission from the SNIA.

• See the speaker notes for this slide for important usage information.

• See SNIA-SSM-colors.ppt for printing and color/graphics conventions.

Copyright © 2000,2003, Storage Networking Industry Association

SNIA shared-storage modelA work in progress …

An architectural overviewThis revision:• 2001-06-05 last content update• 2003-04-13 last graphics update


Contents

•Purpose•The SNIA storage model

Layers, functions, and servicesNetworks and interfaces

•Applying the SNIA storage modelCommon storage architectures

•Conclusions


Purpose

•Present a simple model for shared storage architectures

•Use it to describe common examples graphically

•Expose, for each one:What services are provided, whereWhere interoperability is required[future] Pros and cons of the architecture


Benefits

•A common “architecture vocabulary”•Reference comparisons between common

solutions•Help to align the industry

Customers can better structure their choicesVendors can better explain their differences


What the model is and is not

• It is not:A specification, an architecture, a design, a product, a recommendation, or an installation

• It is:A framework that captures the functional layers and properties of a storage system


Classic storage model

Application

Storage domain:“anything goes!”

Network?Appliance?

Data mover?Array?

NAS?

JBOD?


File/record layerFile/record layer

Block layerBlock layer

Storage devices (disks, …)Storage devices (disks, …)

Database(dbms)

File system(FS)

The SNIA shared storage modelS

tora

ge

do

ma

in

Ser

vice

sS

ervi

ces

Network

Host

DeviceBlock aggregation

Application



The SNIA storage model:File/record layer

Database(dbms)

File system(FS)


The SNIA storage model:File/record layer — functions

•Aka “access methods”File system, database

•Primary responsibility: packing many smaller things into a few larger ones

Fine-grain naming, space allocation

•Secondary responsibilitiesCaching for performanceCoherency in distributed systems


The SNIA storage model:Block layer



Block aggregationBlock aggregation


The SNIA storage model:Block layer — functions

• Storage devices – storing datadisk drives, tape drives, solid-state disks, …

• Block aggregation – address mappingin-SN aggregation, or “virtualization”slicing & concatenation, stripinglocal & remote mirroring, RAID-n

• Examplesvolume managersdisk array LUs

• Secondary responsibilitiescaching



Database(dbms)

File system(FS)


The SNIA storage model:Access path examples



Note: all 8 possible paths can be used!

Note: all 8 possible paths can be used!

Application


Block layer

•Block-mapping functions:what can be done

•Functional decomposition:where it can be done

•Sample architectures



Block aggregation

Block aggregation


Block layerWhat can be done

• Space managementmaking a large store from many small onespacking many small stores into one large one

• Stripingfor performance (load balancing, throughput)

• Redundancyfull(local & remote mirroring, RAID-1, -10, …)partial (RAID-3, -4, -5, …)point-in-time copy


Block layerWhere it can be done

•Host-sidelogical volume managersdevice drivers, HBAs

•SN-basedHBAs, specialized SN appliances

•Device-basedarray controllers (e.g., RAID)disk controllers (e.g., sparing)

Storage devicesStorage devices


Network

Host

Device


Block layerHow it is done

•Building blocksinput: vector of blocksoutput: vector of blocks

•Result: building blocks can be stacked

enables the 3 layer model for theblock layerlayers can be nested on one anothercould be extended to more layers

……

…

Block aggregation

Block aggregation


Device block-aggregation

Network block-aggregation

Host block-aggregation

Block layerSample architectures

ApplicationHo

st. w

ith L

VM(+

softw

are R

AID?

)

1. Direct-attach

Disk array

SN

Host

with

LVM

2. SN-attach

File

/reco

rdla

yer

Blo

ckla

yer

3. SN aggregation

Aggregationappliance

Host

,no

LVM

Storage devices


File/record layer

•Byte-mapping functions:what can be done

•Functional decomposition:where it can be done

•Sample architectures

File/record layerFile/record layerDatabase

(dbms)File system

(fs)


File/record layerWhat can be done

• Database management systemstuples → tablestables → table-spacestable-spaces → volume

• File systemsfiles → volume

• New typeshttp caches: a kind of distributed file system?


device

File/record layerWhere it can be done

•Host-sidefile systems and databasesNFS, CIFS, etc. are client-server splits inside the file system

•SN-basedNAS head

•Device-basedNAS functions in array box

NAS

Hos

t with

NFS

/CIF

Scl

ient

Hos

t with

loca

lFS

/dbm

s





File/record layer

Host

. with

LVM

and

softw

are R

AID

1. Direct-attach

File

/reco

rdla

yer

Blo

ckla

yer

NASserver

4. NAS server

Host

. with

LVM

Disk array

2. SN-attach

Host3. NAS head

NAS head

Host

LAN

Application

SN


File/record layerFile/record layerDatabase

(dbms)File system

(fs)

The SNIA storage modelA layered view

IV. ApplicationIII. File/record layer

IIIa. DatabaseIIIb. File system

II. Block aggregationIIa. HostIIb. NetworkIIc. Device

I. Storage devices

Storage devicesStorage devices


Application

Network

Host

Device

IV

III

IIcIIbIIa

I


Sto

rag

e d

om

ain



The SNIA storage modelServices subsystem

Application



Database(dbms)

File system(fs)

Ser

vice

sS

ervi

ces

Dis

cove

ry, m

onito

ring

Dis

cove

ry, m

onito

ring

Res

ourc

e m

gmt,

conf

igur

atio

nR

esou

rce

mgm

t, co

nfig

urat

ion

Sec

urity

, bill

ing

Sec

urity

, bill

ing

Red

unda

ncy

mgm

t (ba

ckup

, …)

Red

unda

ncy

mgm

t (ba

ckup

, …)

Hig

h av

aila

bilit

y (fa

il-ov

er, …

)H

igh

avai

labi

lity

(fail-

over

, …)

Cap

acity

pla

nnin

gC

apac

ity p

lann

ing


Services

• Operations off the critical pathnaming, discovery, monitoring, configuration, security, billing,redundancy management (backup, …), high availability management (fail-over, …), capacity planning, …strong ties into system-wide management services

• Vital for successful operationand a major opportunity for SNIA …

… but not discussed further in this presentation





Caching… can be added to almost any layer

Host

. with

LVM

and

softw

are R

AID

File

/reco

rdla

yer

Blo

ckla

yer

Host

NAS head

Host

Host

. with

LVM

Disk array

SN

NAS head

LAN

Ideally, caching only affects performance. But: coherency implications do affect management (protocols, interfaces)

Ideally, caching only affects performance. But: coherency implications do affect management (protocols, interfaces)

Application

Cache

Cache

Cache

Cache

Cacheappliance

Cache





ClusteringInter-box aggregation

Host

. with

LVM

and

softw

are R

AID

File

/reco

rdla

yer

Blo

ckla

yer

Host

NAS head

Host

Host

. with

LVM

Disk array

SN

NAS head

LAN

Cluster FS

Multi-node LVM

Purposes:• load spreading across peers (scalability)

• alternate paths (high availability, scalability)

Purposes:• load spreading across peers (scalability)

• alternate paths (high availability, scalability)

Application


Q: Data versus storage?A: Putting information into containers

user: data (“learning my preferences”)application: container(“user keystroke history”)

application: data (“user keystroke history file”)file system: container (“byte vector”)

file system: data (“a named file”)volume system: container (“blocks in volume”)

volume system: data (“replicated, striped layout”)disk array: container (“blocks in LU”)


SharingContent sharing or resource sharing?

•Content sharing (“logical”, “data”)contents accessed and understood by multiple clients• e.g., file system, Oracle Parallel Server dbms

some of the hard issues:• coherency• heterogeneous data formats

•Resource sharing (“container”, “physical”)e.g., disk array where hosts access disjoint LUs





SharingContent sharing and resource sharing

Host

with

LVM

File

/reco

rdla

yer

Blo

ckla

yer

Host

with

LVM

SN

NAS system

HostHost

LAN

Application

Resource sharing

Array is shared,but LUs are disjoint

Resource sharing

Array is shared,but LUs are disjoint

Data sharing

NAS system is shared – and so are the files

Data sharing

NAS system is shared – and so are the files


Storage device

Block layer

File layer

Operating System

Application

Networks and interfacesare pervasive in the model

Network or interface

Network

Bus

API

Full benefits come only fromcommon, openinterfaces

Full benefits come only fromcommon, openinterfaces






Networks and interfacesComposition and scaling

Open interfacesallow:1. vertical

composition2. horizontal scaling3. supplier

independence

Open interfacesallow:1. vertical

composition2. horizontal scaling3. supplier

independence

Network

Bus

API

API

Network

Bus

API


Networks and interfacesOpen interfaces require …

•Well defined:functions (what they do)interface protocols (data formats)access protocols(system call, RPC, flow control, …)

•That are:publishedsupported by multiple products

=> standards (which is where SNIA comes in)

Network

Bus

API


? NAS

Q: “SAN” versus “NAS”?A: a poorly-formed question

• Q: hardware: FibreChannel vs Ethernet vs InfiniBand?

• Q: API: blocks vs files (aka “NAS”)vs objects (OSD)?

• Q: protocol: FCP vs TCP/IP vs … ?• A: (to all the above) it depends …

• Storage network (SN):any (mostly) dedicated network, installed (mostly) for storage trafficwhatever the hardware, API, or protocol

“SAN”

FC E’net

iSCSI

File

s B

lock

s

FC E’net

File

s B

lock

s FS/block combo


Some common storage architectures

Mapping the SNIA model onto some current implementations





Direct-attach block storage

Disk array

Host

,no

LVM

File

/reco

rdla

yer

Blo

ckla

yer

Host

. with

LVM

and

softw

are R

AID

Host

wi

th L

VM

Application • Direct-attach

• Multi-attach boxE.g., SCSI

• Direct-attach

• Multi-attach boxE.g., SCSI





SN-attached block storage

Disk array

Host

,no

LVM

File

/reco

rdla

yer

Blo

ckla

yer

SN

“SN” = any networkused for storage access.E.g., Fibre Channel,Ethernet, …

“SN” = any networkused for storage access.E.g., Fibre Channel,Ethernet, …

Host

with

LVM

Application





SN-attached block storagewith metadata server

Disk array

Host

with

LVM

File

/reco

rdla

yer

Blo

ckla

yer

SNBlock-aggregationmetadata server

Host

,no

LVM

Aggregation map(metadata) issupplied by anexternal server

Aggregation map(metadata) issupplied by anexternal server

Application





Block storage aggregationin a storage network appliance

Disk array

SN

File

/reco

rdla

yer

Blo

ckla

yer


Host

with

LVM Ho

st,

no L

VM

Application aka “SNvirtualization”Functions: LVM, caching

aka “SNvirtualization”Functions: LVM, caching





Multi-site block storage

Disk array

SNAggregation

appliance

Host

. with

LVM

Application

Disk array


Host

. with

LVM

Application

SN applianceSN appliance

WAN

WAN

Host-to-hostHost-to-host

Functions: point-in-timecopy, caching, local & remote mirroring, …

Functions: point-in-timecopy, caching, local & remote mirroring, …

WAN

Device-to-deviceDevice-to-device

File

/reco

rdla

yer

Blo

ckla

yer





File server

NAS system

HostHost

File

/reco

rdla

yer

Blo

ckla

yer

LAN-attached“NAS” systemMay do SN/blockaggregation, etc. insidein the NAS system box

LAN-attached“NAS” systemMay do SN/blockaggregation, etc. insidein the NAS system box

Application

LAN

privateSN?





File server controller(“NAS head”)

NAS head

Disk array

File

/reco

rdla

yer

Blo

ckla

yer

No storage in thefile server controller box

No storage in thefile server controller boxHostHost

LAN

Application

SN





NAS/file server metadata manager (“asymmetric”)

Disk array

File

/reco

rdla

yer

Blo

ckla

yer

Hosts get file meta-data from FS/NAS controller, thenaccess the data directly

Hosts get file meta-data from FS/NAS controller, thenaccess the data directly

Host

. with

LVM

Filemetadata

Blockaccesses

FS controller canalso be NAS serverFS controller canalso be NAS server

HostLAN

SN

Application

File system metadata





Object-based Storage Device (OSD), CMU NASD

OSDdevice

File

/reco

rdla

yer

Blo

ckla

yer

Host

Object metadata

Host

Application

LAN

Securitymetadata

Filemetadata


Summary & conclusions



Database(dbms)

File system(FS)

The SNIA shared storage modelSt

orag

e do

mai

n



Serv

ices

Serv

ices

Dis

cove

ry, m

onito

ring

Dis

cove

ry, m

onito

ring

Res

ourc

e m

gmt,

conf

igur

atio

nR

esou

rce

mgm

t, co

nfig

urat

ion

Sec

urity

, bill

ing

Sec

urity

, bill

ing

Red

unda

ncy

mgm

t (ba

ckup

, …)

Red

unda

ncy

mgm

t (ba

ckup

, …)

Hig

h av

aila

bilit

y (fa

il-ov

er, …

)H

igh

avai

labi

lity

(fail-

over

, …)

Cap

acity

pla

nnin

gC

apac

ity p

lann

ing

Application

Network

Host

DeviceBlock aggregation





Block layerSample architectures

Host

. with

LVM

and

softw

are R

AID

1. Direct-attach

SN

Host

. with

LVM

Disk array

2. SN-attach3. SN aggregation


Host

,no

LVM

File

/reco

rdla

yer

Blo

ckla

yer

Application





File/record layerSample architectures

Host

. with

LVM

and

softw

are R

AID

1. Direct-attach

File

/reco

rdla

yer

Blo

ckla

yer

NASserver

4. NAS serverHost3. NAS head

NAS head

Host

LANHo

st. w

ith L

VM

Disk array

SN

2. SN-attachApplication


Uses for the model

•Vendorsplace products in the space of architecturesclarify product differences

•Customersunderstand vendor offerings better

•The industrybasis for common definitions, communication, understanding, interoperability


Conclusions

• The SNIA shared storage model is both simple and useful

to highlight similarities and differencesas a basis for comparisons

• Still a work in progressdata movers, tape drives, …better comparisons …suggestions?

• The SNIA-TC welcomes input:<[email protected]>


Authors

• John Wilkes, Hewlett-Packard (project lead)• Harald Skardal, NetApps• David Black, EMC• Wayne Rickard (SNIA TC chairperson), Gadzoox• Co-conspirators: the rest of the SNIA Technical

CouncilDave Anderson, Seagate TechnologyJim Carlson, IBMGarth Gibson, CMU/PanasasKevin Phaup, HighGround SystemsDavid Thiel, Compaq

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