1. Intelligent Storage Systems
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Intelligent Storage Systems
Chapter 4
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2. Copyright © 2009 EMC Corporation. Do not Copy - All Rights Reserved.
Chapter objective
After completing this chapter, you will be able to:
Describe components of intelligent storage system
List benefits of intelligent storage system
Explain intelligent cache algorithms and protection
Describe intelligent storage array implementation
High-end storage array
Mid-range storage array
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3. What is an Intelligent Storage System
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What is an Intelligent Storage System
Intelligent Storage Systems are RAID arrays that are:
Highly optimized for I/O processing
Have large amounts of cache for improving I/O performance
Have operating environments that provide:
Intelligence for managing cache
Array resource allocation
Connectivity for heterogeneous hosts
Advanced array based local and remote replication options
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4. Benefits of an Intelligent Storage System
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Benefits of an Intelligent Storage System
Intelligent storage system provides several benefits over a collection of disks in an array (JBOD) or even a RAID arrays:
Increased capacity
Improved performance
Easier data management
Improved data availability and protection
Enhanced Business Continuity support
Improved security and access control
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5. Components of an Intelligent Storage System
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Components of an Intelligent Storage System
Intelligent Storage System
Host
Front End
Back End
Physical Disks
Cache
Connectivity
FC SAN
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6. Intelligent Storage System: Front End
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Intelligent Storage System: Front End
Intelligent Storage System
Host
Front End
Back End
Physical Disks
Cache
Connectivity
FC SAN
Ports
Controllers
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7. Front End Command Queuing
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Front End Command Queuing A D C B A D C B A C D
I/O Requests
I/O Processing B
Order
Front-End
Cylinders
Controller
Without Optimization (FIFO) A D C B A D B C A D
I/O Requests
I/O Processing C B
Order
Front-End
Cylinders
Controller
With command queuing
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8. Intelligent Storage System: Cache
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Intelligent Storage System: Cache
Intelligent Storage System
Host
Front End
Back End
Physical Disks
Cache
Connectivity
FC SAN
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9. Write Operation with Cache
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Write Operation with Cache
Write-through Cache
Cache
Write Request
Acknowledgement
Write-back
Cache
Write Request
Acknowledgement
Acknowledgement
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10. Read Operation with Cache: ‘Hits’ and ‘Misses’
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Read Operation with Cache: ‘Hits’ and ‘Misses’
Data found in cache = ‘Hit’
Cache
Read Request
No data found = ‘Miss’
Cache
Read Request
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11. Cache Management: Algorithms
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Cache Management: Algorithms
Least Recently Used (LRU)
Discards least recently used data
Most Recently Used (MRU)
Discards most recently used data
( assumed that recent data may not be required for a while)
New Data
Oldest Data
Cache Implementation
Dedicated Cache
Separate memory sets reserved for read and write
Global Cache
Both read and write operation use available memory.
More efficient
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12. Cache Management: Watermarking
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Cache Management: Watermarking
Manage peak I/O requests “bursts” through flushing/de-staging
Idle flushing, High Watermark flushing and Forced flushing
For maximum performance:
Provide headroom in write cache for I/O bursts
100 %
HWM
LWM
Idle flushing
High watermark flushing
Forced flushing
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Cache Data Protection
Protecting cache data against failure: (power failure)
Cache mirroring
Each write to the cache is held in two different memory locations on two independent memory cards
Cache coherency(only writes r mirrored)
Cache vaulting
Cache is exposed to the risk of uncommitted data loss due to power failure
In the event of power failure, uncommitted data is dumped to a dedicated set of drives called vault drives
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14. Intelligent Storage System: Back End
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Intelligent Storage System: Back End
Intelligent Storage System
Host
Front End
Back End
Physical Disks
Cache
Connectivity
FC SAN
Controllers
Ports
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15. Intelligent Storage System: Physical Disks
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Intelligent Storage System: Physical Disks
Intelligent Storage System
Host
Front End
Back End
Physical Disks
Cache
Connectivity
FC SAN
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16. What the Host Sees – RAID Sets and LUNs (Logical Unit Number)
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What the Host Sees – RAID Sets and LUNs (Logical Unit Number)
Host 1
Intelligent Storage System
Front End
Back End
Physical Disks
LUN 0
Cache
Connectivity
LUN 0
FC SAN
LUN 1
LUN 1
Host 2
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LUN Masking
It is a process that provides data access control by defining which LUNs a host can access.
LUN masking is access control mechanism
Process of masking LUNs from unauthorized access
Implemented on storage arrays and at front end controller
Intelligent Storage Arrays
High End Storage System
Mid Range Storage System
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18. ISS Implementation: High-end Storage Systems
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ISS Implementation: High-end Storage Systems
Also referred as Active-active arrays
I/O’s are serviced through all the available path
Following are high-end array capabilities:
Large storage capacity
Huge cache to service host I/Os
Fault tolerance architecture
Multiple front-end ports and support to interface protocols
High scalability
Ability to handle large amounts of concurrent I/Os
Designed for large enterprises
Active-Active Configuration
Controller A
Port
Active
LUN
Controller B
Port
Active
Host
Storage
Array
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19. Midrange Storage Systems
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Midrange Storage Systems
Also referred as Active-passive arrays
Host can perform I/Os to LUNs only through active paths
Other paths remain passive till active path fails
Midrange array have two controllers, each with cache, RAID controllers and disks drive interfaces
Designed for small and medium enterprises
Less scalable as compared to high-end array
Active-Passive Configuration
Controller A
Port
Active
LUN
Controller
Port B
Passive
Host
Storage
Array
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20. Copyright © 2009 EMC Corporation. Do not Copy - All Rights Reserved.
Chapter Summary
Key points covered in this chapter:
Intelligent Storage Systems features
Components of Intelligent Storage Systems
Cache management algorithms
Intelligent Storage System implementation
High-end storage array
Mid range storage array
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21. Concept in Practice: EMC CLARiiON CX-4
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Concept in Practice: EMC CLARiiON CX-4
Support for UltraFlex technology
Scalable from up to 960 disks
Supports flash drives
Supports different types and sizes of drives, and RAID types (0, 1, 1+0, 3, 5, 6)
Supports up to 16 GB of available cache memory per controller (Storage Processor)
Enhances availability with non disruptive upgrade and failover
Ensures data protection through mirrored write cache and cache vaulting
Supports storage-based local and remote data replication
Through SnapView and MirrorView software
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22. CLARiiON CX-4 Architecture
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CLARiiON CX-4 Architecture
CPU
Memory
CPU Module
Multi-Core Processors
FC Module
I/O Complex
iSCSI Module
4 Gb/s Fibre
Channel Back-End
CLARiiON Messaging Interface (CMI)
Multi-Lane PCI-Express Bridge Link
Power Supply
SPS
Fan
4 Gb/s LCC
4 Gb/s Fibre Channel Front-End
Storage Processor
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23. Copyright © 2009 EMC Corporation. Do not Copy - All Rights Reserved.
EMC Symmetrix DMX-4
Incrementally scalable to 2,400 disks
Supports Flash-based solid-state drives
Dynamic global cache memory (16 GB–512 GB)
Advanced processing power (up to 130 PowerPC)
Direct matrix Architecture
High data processing bandwidth (up to 128 GB/s)
Data protection with RAID 1, 1+0 (also known as 10 for mainframe), 5, and 6
Storage-based local and remote replication
Through TimeFinder and SRDF software
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24. Direct Matrix Architecture
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Direct Matrix Architecture
ESCON host attach
Fibre Channel host attach
FICON, GigE, iSCSI host attach
FICON, GigE, iSCSI host attach
FICON, GigE, iSCSI host attach
FICON, GigE, iSCSI host attach
Fibre Channel host attach
ESCON host attach
ESCON Director
FC Director
Multi-Protocol CD
Multi-Protocol CD
Multi-Protocol CD
Multi-Protocol CD
FC Director
ESCON Director
Cntl
Cntl
Cntl
Cntl
Cntl
Cntl
Cntl
Cntl
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Direct
Matrix
Control and communications Signals
Environmental
control and
status signals
64 GB
Memory
64 GB
Memory
64 GB
Memory
64 GB
Memory
64 GB
Memory
64 GB
Memory
64 GB
Memory
64 GB
Memory
Environmental
control and
status signals
Control and communications Signals
FC (Back-End)
Direct
Matrix
Direct
Matrix
FC (Back-End)
Direct
Matrix
Direct
Matrix
FC (BE or FE)
Direct
Matrix
Direct
Matrix
FC (BE or FE)
Direct
Matrix
Direct
Matrix
FC (BE or FE)
Direct
Matrix
Direct
Matrix
FC (BE or FE)
Direct
Matrix
Direct
Matrix
FC (Back-End)
Direct
Matrix
Direct
Matrix
FC (Back-End)
Direct
Matrix
Direct
Matrix
Cntl
Cntl
Cntl
Cntl
Cntl
Cntl
Cntl
Cntl A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B A B
Symmetrix
Fibre Channel disk devices
Symmetrix
Fibre Channel disk devices
Fibre Channel
back-end
director *
Fibre Channel
back-end
director *
Fibre Channel
back-end
director *
Fibre Channel
back-end
director *
Symmetrix
Fibre Channel disk devices
Symmetrix
Fibre Channel disk devices
Power supplies
Battery backup
Unit Modules
Cooling
Service
Processor
Modem
UPS
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25. Copyright © 2009 EMC Corporation. Do not Copy - All Rights Reserved.
Check Your Knowledge 
What are the parts of an Intelligent Storage System?
What are the differences between a high-end and midrange storage array?
What is the difference between a read cache hit and a read cache miss?
What is the difference between Least Recently Used and Most Recently Used algorithms?
What is the difference between Write-through and Write-back cache?
ISMDR:BE5IT:VIII:Madhu N. PIIT