Download Storage Decisions 2003

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NAS and Gateways
Considerations for File
Storage
Randy Kerns
Copyright © 2003 - All Rights Reserved
Evaluator Group, Inc
.
7720 E. Belleview Avenue • Suite 210 • Greenwood Village, CO 80111
(303) 221-7867 • Fax: (303) 221-1615
www.evaluatorgroup.com
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Agenda
 Structure of I/O
 File Storage
 Applications – file vs. block
 NAS storage
• Structure
• NAS Gateways
• Considerations
• Evaluation
 NAS Management
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Structure of I/O
 All Open Systems use a similar I/O method
• minor variations
• some terminology differences
• includes all flavors of Unix
• includes NT/2000/XP/2003 Server
 Structure is for a “Layered I/O”
• elements in each layer has different capability
• layers may come from different vendors
• system may contain different elements at each layer
depending on device or usage
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Layered I/O Structure
Application /
Database
Operating System
File System
Device Driver
Interface Hardware
Device
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File Storage
 File System
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•
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/
file and directory structure on
logical disk (typically single)
contains metadata to describe
information (size, location, dates,
etc.) on the disk. Ex: superblock,
inode
different types of file systems with
different methods of access
•
file system handled by software in
program stack of operating system
•
multiple file systems may be
present at one time
•
“mounted” file systems or “shares”
are remote file systems
bin
dev
aps
etc
test
passwd
usr
Mounted
file system
hosts
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File Systems
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VFS
FFS
UFS
AFS
NFS
RFS
S5FS
VxFS
JFS
CFS
EXT2/EXT3
GFS
ReiserFS
XFS
CXFS
QFS
HFS
NTFS
FATxx
Virtual File System
Fast File System
UNIX File System – used interchangeably with FFS
Andrew File System – also Distributed File System
Network File System – developed by Sun
Remote File System – developed by AT&T
Original System V file system
Veritas Journaling File System
Journaled File System – AIX
Cluster file system – Tru64
2nd/3rd Extended File System – Linux systems
Global File System – Linux
Journaling file system – Linux
Extended File System – SGI and others
Clustered Extended File System – SGI
64-bit very large file system – Sun Solaris
Hierarchical File System – S/390 UNIX
Windows NT/2000/2003
Windows – several versions
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Applications
 May be written to do file I/O or block I/O
• File I/O
 Uses the file system driver
 Caching done by system
 Typically system utilities for management
 I/O done to FILE HANDLE: Offset
•
Block I/O
 Used to bypass file system – performance reasons
and overhead in capacity
 Buffering/caching done by application (ie database)
 Called RAW I/O
 I/O typically done to blocks – linear address space
 Special utilities for management
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Network Attached Storage
Workstation
Workstation
Host
Tower box
LAN
I/O Requests for
for File I/O using
NFS, CIFS
Server
Server owns storage
device and does block
level I/O
NAS
Storage
Disk array
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NAS Device
NAS File Access Handler
Application
File I/O Access
File I/O
Operating System
I/O Redirector
Operating System
NAS I/O Structure
Client Computer System
Network File Protocol
(NFS, CIFS)
TCP/IP Stack
NIC Driver
File
System
TCP/IP
Stack
Volume
Manager
NIC
Driver
Disk
System
Device
Driver
Network
Interface
Card
Network Interface Card
Remote File I/O
Access Across
the Network
Network
File
Protocol
(NFS,
CIFS)
Disk
Controller/
HBA
Block I/O
LAN
Disk System
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NAS Gateways
Network Attached Storage with SAN Storage
Application
 The controller function of
NAS with the storage
decoupled
• Connected to a SAN – fibre channel
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•
•
typically
May be separate product or a
version of a standard NAS product
can utilize SAN capabilities
does introduce a different
management scheme – adds the
SAN storage management as well
as the NAS administration
File
Redirector
Computer
System
Local Area Network
Remote
File System
NAS Device
SAN
Disk
System
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NAS Gateways
 Typical usage profile
• Enterprise data center environments with existing SAN
 Requirement for file storage
 Consolidation of existing, independent NAS devices
 Centralized administration and purchasing
 Storage system partitioned for NAS filesystems
(LUNs)
•
Administration cost
 Target is to reduce overall storage administration
costs
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NAS Considerations
 FIRST: What are your requirements?
• Part of overall storage strategy
 Future needs
 Timeframe for deployment
 Cost structures
•
Understand needs for users, applications, business
 Does application require file or block access?
 What environment will it used in?
• Enterprise data center
• Small to Mid-Size Business (SMB)
• Departmental
• Workgroup
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NAS Considerations
 Who will administer
• Dictates tools and capabilities
• Organizational tension
 Usage considerations
• Protocols – CIFS, NFS, HTTP, FTP, NCP
• Data sharing – locking requirements
• Connectivity – number and type of connections
• Security – IP/Ethernet usage, data at rest
• Performance
 Types of data - bandwidth or response time sensitive
• OLTP
• Large Block – video, etc.
 Responsiveness – guarantees, application
requirements
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NAS Considerations
 Advanced services
• Part of consideration
• Requirements dictate which are of concern
 Remote copy for disaster tolerance: Technology
used, distance, cost, currency of data, recovery
process, time to recovery
 Point-in-Time copy functions: Local and remote,
capacity consumed, ability to restore versions, make
available read/write
 Backup: LAN-free, use of SAN devices, NDMP
support, favorite backup software usage
 Management: incorporation into overall storage
management strategy, aggregation
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NAS Considerations
 Capacity required
• Today and tomorrow
• Scaling issues
 Additional NAS devices vs. additional disks
 Performance scaling
 Management
 Is a NAS Gateway the best option ?
• Usually environment specific
 Enterprise data center with existing SAN
 Storage professionals managing storage
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NAS Evaluation
 Develop a set of criteria
• Put in elements that are part of your requirements
• Give little weight to extraneous items (So What?)
 Evaluator Group workbook
• As example
• EG_NAS_Workbook.pdf
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NAS Management
 Evolution
• NAS devices each individually managed
 Installed and administered as unique devices
•
Management does not scale
 Additive costs for additional NAS devices
•
Few sophisticated tools
 Expectation for capacity planning, performance
monitoring and reporting, and SLA adherence didn’t
exist
•
Changes are underway for NAS management
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NAS Management
 Aggregation
• Management software to manage multiple NAS devices
• Two methods
 Individual devices with information accumulated
• Statistics, capacity information
• Controls, status
 Multiple devices managed as single entity
• Dynamic allocation of capacity – adding of capacity
(units)
• Data protection dynamically spread among devices
• Performance tuning by distributing data
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NAS Management
 NAS Aggregation
Example
• Software to collect information
•
•
about NAS appliances
 Same vendor
Unified view to monitor and
control
 Status and events
 Capacity
 Appliances, OS versions
 Volumes
 Disk devices
Addresses admin costs in
homogeneous environment
Servers
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NAS Management
 NAS Aggregation Example
• Data accessed as if single NAS
Servers
appliance – NAS array
•
For increased capacity, add
appliances
•
Data is redistributed across
appliances
•
Clients see additional capacity
with no required changes
•
Management as a single entity
NAS Appliances
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NAS Management
 Summary
• NAS Management is maturing
• Economics of management / administration cost is now
becoming important
 Necessary with expanded use of NAS
 Capacity growth accentuate the problem
•
Need to integrate with SRM tools
 Must include NAS devices from different vendors
 Still a long way to go to have enterprise tools
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NAS Summary
 Choice of NAS is an easy answer in some
environments
• Traditional NAS usage in departmental and workgroups
• More difficult in enterprise data center environments
 Where the requirements are understood and the
attributes of NAS answer them
 Where the overall storage strategy can incorporate
NAS into existing environment
• Includes management tools
• Infrastructure
• Costs – separate IP network, NIC changes
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