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Transcript of Copyright © 2000,2003, Storage Networking Industry Association
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 must conform to usage notes in the speaker noted for this slide.
• 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 overview
This revision:
• 2001-06-05 last content update
• 2003-04-13 last graphics update
3 Copyright © 2000,2003, Storage Networking Industry Association
Contents
• Purpose
• The SNIA storage model Layers, functions, and services Networks and interfaces
• Applying the SNIA storage model Common storage architectures
• Conclusions
4 Copyright © 2000,2003, Storage Networking Industry Association
Purpose
• Present a simple model for shared storage architectures
• Use it to describe common examples graphically
• Expose, for each one: What services are provided, where Where interoperability is required [future] Pros and cons of the architecture
5 Copyright © 2000,2003, Storage Networking Industry Association
Benefits
• A common “architecture vocabulary”
• Reference comparisons between common solutions
• Help to align the industry Customers can better structure their choices Vendors can better explain their differences
6 Copyright © 2000,2003, Storage Networking Industry Association
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
7 Copyright © 2000,2003, Storage Networking Industry Association
Classic storage model
Application
Storage domain:“anything goes!”
Network?Appliance?
Data mover?
Array?
NAS?
JBOD?
8 Copyright © 2000,2003, Storage Networking Industry Association
File/record layer
Block layer
Storage devices (disks, …)
Database(dbms)
File system(FS)
The SNIA shared storage modelS
tora
ge
do
ma
in
Ser
vice
s
Network
Host
DeviceBlock aggregation
Application
9 Copyright © 2000,2003, Storage Networking Industry Association
File/record layer
The SNIA storage model:File/record layer
Database(dbms)
File system(FS)
10 Copyright © 2000,2003, Storage Networking Industry Association
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 responsibilities Caching for performance Coherency in distributed systems
11 Copyright © 2000,2003, Storage Networking Industry Association
The SNIA storage model:Block layer
Block layer
Storage devices (disks, …)
Block aggregation
12 Copyright © 2000,2003, Storage Networking Industry Association
The SNIA storage model:Block layer — functions
• Storage devices – storing data disk drives, tape drives, solid-state disks, …
• Block aggregation – address mapping in-SN aggregation, or “virtualization” slicing & concatenation, striping local & remote mirroring, RAID-n
• Examples volume managers disk array LUs
• Secondary responsibilities caching
13 Copyright © 2000,2003, Storage Networking Industry Association
File/record layer
Database(dbms)
File system(FS)
Block layer
The SNIA storage model:Access path examples
Storage devices (disks, …)
Block aggregation
Note: all 8 possible paths can be used!
Application
14 Copyright © 2000,2003, Storage Networking Industry Association
Block layer
• Block-mapping functions:what can be done
• Functional decomposition:where it can be done
• Sample architectures
Block layer
Storage devices (disks, …)
Block aggregation
15 Copyright © 2000,2003, Storage Networking Industry Association
Block layerWhat can be done
• Space management making a large store from many small ones packing many small stores into one large one
• Striping for performance (load balancing, throughput)
• Redundancy full (local & remote mirroring, RAID-1, -10, …) partial (RAID-3, -4, -5, …) point-in-time copy
16 Copyright © 2000,2003, Storage Networking Industry Association
Block layerWhere it can be done
• Host-side logical volume managers device drivers, HBAs
• SN-based HBAs, specialized SN appliances
• Device-based array controllers (e.g., RAID) disk controllers (e.g., sparing)
Storage devices
Block aggregation
Network
Host
Device
17 Copyright © 2000,2003, Storage Networking Industry Association
Block layerHow it is done
• Building blocks input: vector of blocks output: vector of blocks
• Result: building blocks can be stacked enables the 3 layer model for the
block layer layers can be nested on one another could be extended to more layers
……
…
Block aggregation
18 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Block layerSample architectures
ApplicationH
ost.
with
LVM
(+ s
oftw
are
RA
ID?)
1. Direct-attach
Disk array
SN
Hos
tw
ith L
VM
2. SN-attach
File
/rec
ord
lay
erB
lock
lay
er
3. SN aggregation
Aggregationappliance
Hos
t,no
LVM
Storage devices
19 Copyright © 2000,2003, Storage Networking Industry Association
File/record layer
• Byte-mapping functions:what can be done
• Functional decomposition:where it can be done
• Sample architectures
File/record layerDatabase(dbms)
File system(fs)
20 Copyright © 2000,2003, Storage Networking Industry Association
File/record layerWhat can be done
• Database management systems tuples → tables tables → table-spaces table-spaces → volume
• File systems files → volume
• New types http caches: a kind of distributed file system?
21 Copyright © 2000,2003, Storage Networking Industry Association
device
File/record layerWhere it can be done
• Host-side file systems and databases NFS, CIFS, etc. are client-server
splits inside the file system
• SN-based NAS head
• Device-based NAS functions in array box
NAS
Ho
st w
ith
NF
S/C
IFS
clie
nt
Ho
st w
ith
lo
cal
FS
/db
ms
22 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
File/record layer
Hos
t. w
ith L
VMan
d so
ftwar
e R
AID
1. Direct-attach
File
/re
cord
lay
er
Blo
ckla
ye
r
NASserver
4. NAS server
Hos
t. w
ith L
VM
Disk array
2. SN-attach
Host3. NAS head
NAS head
Host
LAN
Application
SN
23 Copyright © 2000,2003, Storage Networking Industry Association
File/record layerDatabase(dbms)
File system(fs)
The SNIA storage modelA layered view
IV. Application
III. File/record layerIIIa. DatabaseIIIb. File system
II. Block aggregationIIa. HostIIb. NetworkIIc. Device
I. Storage devices
Storage devices
Block aggregation
Application
Network
Host
Device
IV
III
IIc
IIb
IIa
I
24 Copyright © 2000,2003, Storage Networking Industry Association
Sto
rage
do
ma
in
File/record layer
Block layer
The SNIA storage modelServices subsystem
Application
Storage devices (disks, …)
Block aggregation
Database(dbms)
File system(fs)
Ser
vice
sD
isco
very
, mon
itorin
gR
esou
rce
mgm
t, c
onfig
urat
ion
Sec
urity
, bi
lling
Red
unda
ncy
mgm
t (b
acku
p, …
)H
igh
avai
labi
lity
(fai
l-ove
r, …
)C
apac
ity p
lann
ing
25 Copyright © 2000,2003, Storage Networking Industry Association
Services
• Operations off the critical path naming, 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 operation and a major opportunity for SNIA … … but not discussed further in this presentation
26 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Caching… can be added to almost any layer
Hos
t. w
ith L
VMan
d so
ftwar
e R
AID
File
/re
cord
lay
er
Blo
ckla
ye
r
Host
NAS head
Host
Hos
t. w
ith L
VM
Disk array
SN
NAS head
LAN
Ideally, caching only affects performance.
But: coherency implications do affect management (protocols, interfaces)
Application
Cache
Cache
Cache
Cache
Cacheappliance
Cache
27 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
ClusteringInter-box aggregation
Hos
t. w
ith L
VMan
d so
ftwar
e R
AID
File
/re
cord
lay
er
Blo
ckla
ye
r
Host
NAS head
Host
Hos
t. w
ith L
VM
Disk array
SN
NAS head
LAN
Cluster FS
Multi-node LVM
Purposes:• load spreading across peers (scalability)
• alternate paths (high availability, scalability)
Application
28 Copyright © 2000,2003, Storage Networking Industry Association
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”)
29 Copyright © 2000,2003, Storage Networking Industry Association
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
30 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
SharingContent sharing and resource sharing
Hos
tw
ith L
VM
File
/rec
ord
lay
erB
lock
lay
er
Hos
tw
ith L
VM
SN
NAS system
HostHost
LAN
Application
Resource sharing
Array is shared,but LUs are disjoint
Data sharing
NAS system is shared – and so are the files
31 Copyright © 2000,2003, Storage Networking Industry Association
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, open interfaces
32 Copyright © 2000,2003, Storage Networking Industry Association
Network or interface
Network or interface
Network or interface
Network or interface
Networks and interfacesComposition and scaling
Open interfaces allow:1. vertical composition2. horizontal scaling3. supplier independence
Network
Bus
API
API
Network
Bus
API
33 Copyright © 2000,2003, Storage Networking Industry Association
Networks and interfacesOpen interfaces require …
• Well defined: functions (what they do) interface protocols (data formats) access protocols
(system call, RPC, flow control, …)
• That are: published supported by multiple products=> standards (which is where SNIA comes in)
Network
Bus
API
34 Copyright © 2000,2003, Storage Networking Industry Association
? 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 traffic whatever the hardware, API, or protocol
“SAN”
FC E’net
iSCSI
Fil
es
Blo
cks
FC E’net
Fil
es
Blo
cks FS/block com
bo
Copyright © 2000,2003, Storage Networking Industry Association
Some common storage architectures
Mapping the SNIA model onto some current implementations
36 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Direct-attach block storage
Disk array
Hos
t,no
LVM
File
/rec
ord
lay
erB
lock
lay
er
Hos
t. w
ith L
VMan
d so
ftwar
e R
AID
Hos
t w
ith L
VM
Application • Direct-attach
• Multi-attach box
E.g., SCSI
37 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
SN-attached block storage
Disk array
Hos
t,no
LVM
File
/rec
ord
lay
erB
lock
lay
er
SN
“SN” = any networkused for storage access.E.g., Fibre Channel,Ethernet, …
Hos
t with
LVM
Application
38 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
SN-attached block storagewith metadata server
Disk array
Hos
t with
LVM
File
/rec
ord
lay
erB
lock
lay
er
SNBlock-aggregation
metadata server
Hos
t,no
LVM
Aggregation map(metadata) issupplied by anexternal server
Application
39 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Block storage aggregationin a storage network appliance
Disk array
SN
File
/rec
ord
lay
erB
lock
lay
er
Aggregationappliance
Hos
tw
ith L
VM Hos
t,no
LVM
Application aka “SNvirtualization”
Functions: LVM, caching
40 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Multi-site block storage
Disk array
SNAggregation
appliance
Hos
t. w
ith L
VM
Application
Disk array
Aggregationappliance
Hos
t. w
ith L
VM
Application
SN appliance
WAN
WAN
Host-to-host
Functions: point-in-timecopy, caching, local & remote mirroring, …
WAN
Device-to-device
File
/re
cord
laye
rB
lock
laye
r
41 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
File server
NAS system
HostHost
File
/re
cord
lay
er
Blo
ckla
ye
r
LAN-attached“NAS” system
May do SN/blockaggregation, etc. insidein the NAS system box
Application
LAN
privateSN?
42 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
File server controller(“NAS head”)
NAS head
Disk array
File
/re
cord
lay
er
Blo
ckla
ye
r
No storage in thefile server controller boxHostHost
LAN
Application
SN
43 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
NAS/file server metadata manager (“asymmetric”)
Disk array
File
/re
cord
lay
er
Blo
ckla
ye
r
Hosts get file meta-data from FS/NAS controller, thenaccess the data directly
Hos
t. w
ith L
VM
Filemetadata
Blockaccesses
FS controller canalso be NAS server
HostLAN
SN
Application
File system metadata
44 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Object-based Storage Device (OSD), CMU NASD
OSDdevice
File
/re
cord
lay
er
Blo
ckla
ye
r
Host
Object metadata
Host
Application
LAN
Securitymetadata
Filemetadata
Copyright © 2000,2003, Storage Networking Industry Association
Summary & conclusions
46 Copyright © 2000,2003, Storage Networking Industry Association
File/record layer
Database(dbms)
File system(FS)
The SNIA shared storage modelS
tora
ge
do
ma
in
Block layer
Storage devices (disks, …)
Se
rvic
es
Dis
cove
ry, m
onito
ring
Res
ourc
e m
gmt,
con
figur
atio
nS
ecur
ity,
billi
ngR
edun
danc
y m
gmt
(bac
kup,
…)
Hig
h av
aila
bilit
y (f
ail-o
ver,
…)
Cap
acity
pla
nnin
g
Application
Network
Host
DeviceBlock aggregation
47 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
Block layerSample architectures
Hos
t. w
ith L
VMan
d so
ftwar
e R
AID
1. Direct-attach
SN
Hos
t. w
ith L
VM
Disk array
2. SN-attach3. SN aggregation
Aggregationappliance
Hos
t,no
LVM
File
/rec
ord
lay
erB
lock
lay
er
Application
48 Copyright © 2000,2003, Storage Networking Industry Association
Device block-aggregation
Network block-aggregation
Host block-aggregation
File/record layerSample architectures
Hos
t. w
ith L
VMan
d so
ftwar
e R
AID
1. Direct-attach
File
/re
cord
lay
er
Blo
ckla
ye
r
NASserver
4. NAS serverHost
3. NAS head
NAS head
Host
LANH
ost.
with
LVM
Disk array
SN
2. SN-attachApplication
49 Copyright © 2000,2003, Storage Networking Industry Association
Uses for the model
• Vendors place products in the space of architectures clarify product differences
• Customers understand vendor offerings better
• The industry basis for common definitions, communication,
understanding, interoperability
50 Copyright © 2000,2003, Storage Networking Industry Association
Conclusions
• The SNIA shared storage model is both simple and useful to highlight similarities and differences as a basis for comparisons
• Still a work in progress data movers, tape drives, … better comparisons … suggestions?
• The SNIA-TC welcomes input: <[email protected]>
51 Copyright © 2000,2003, Storage Networking Industry Association
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 Council Dave Anderson, Seagate Technology Jim Carlson, IBM Garth Gibson, CMU/Panasas Kevin Phaup, HighGround Systems David Thiel, Compaq