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Table of Contents
                            3PAR Fast RAID: High Performance Without Compromise
	Karl L. Swartz
1  Introduction
2 RAID Basics
	2.1 RAID on Physical Drives: Random Writes
	2.2 RAID on Physical Drives: Sequential Writes
	2.3 RAID on Physical Drives: Reads
3 3PAR’s Improved Implementation of RAID
	3.1 Chunklet-based RAID
		3.1.1 Wide Striping for Performance
		3.1.2 Physical Drives Can Hold a Mix of RAID Levels
	3.2 ASIC Speeds Data Movement and Parity Calculations
	3.3 Fast RAID Reconstruction
4 Choosing the Right RAID Level
	4.1 Fast RAID 5
	4.2 SATA Disks and Fast RAID 6
	4.3 High Availability Options
	4.4 Dynamic Optimization: Tuning Volume Configurations
	4.5 Adaptive Optimization: Autonomic Sub-Volume Tuning
5 Summary
                        
Document Text Contents
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3PAR Fast RAID:
High Performance Without Compromise
Karl L. Swartz





Document Abstract:

3PAR® Fast RAID allows the 3PAR InServ® Storage Server to deliver higher performance with
less hardware, reducing storage costs compared to traditional storage arrays. This paper
describes the components and specific benefits of 3PAR’s improved implementation of RAID
storage, then helps the reader evaluate and select the best RAID level for each volume.


Part Number: raid-wp-10.0

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© 2010 3PAR Inc. All rights reserved. 3PAR, the 3PAR logo, Serving Information, InServ, InForm, InSpire, and Thin Built In are all
trademarks or registered trademarks of 3PAR Inc. All other trademarks and registered trademarks are the property of their
respective owners.




Table of Contents

3PAR Fast RAID: High Performance Without Compromise ........................................................ 1

1 Introduction ............................................................................................................................... 3

2 RAID Basics ............................................................................................................................. 3
2.1 RAID on Physical Drives: Random Writes ..................................................................... 4
2.2 RAID on Physical Drives: Sequential Writes .................................................................. 4
2.3 RAID on Physical Drives: Reads .................................................................................... 5

3 3PAR’s Improved Implementation of RAID ............................................................................ 5
3.1 Chunklet-based RAID ..................................................................................................... 5

3.1.1 Wide Striping for Performance .................................................................. 5
3.1.2 Physical Drives Can Hold a Mix of RAID Levels ....................................... 6

3.2 ASIC Speeds Data Movement and Parity Calculations ................................................ 6
3.3 Fast RAID Reconstruction .............................................................................................. 6

4 Choosing the Right RAID Level .............................................................................................. 7
4.1 Fast RAID 5 ..................................................................................................................... 8
4.2 SATA Disks and Fast RAID 6 ......................................................................................... 8
4.3 High Availability Options .................................................................................................. 9
4.4 Dynamic Optimization: Tuning Volume Configurations ............................................... 10
4.5 Adaptive Optimization: Autonomic Sub-Volume Tuning ............................................. 10

5 Summary ................................................................................................................................ 10

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© 2010 3PAR Inc. All rights reserved. 3PAR, the 3PAR logo, Serving Information, InServ, InForm, InSpire, and Thin Built In are all
trademarks or registered trademarks of 3PAR Inc. All other trademarks and registered trademarks are the property of their
respective owners.




For example, consider a host write of 6 blocks of data. RAID 1 will require 12 disk I/Os, while the
default configurations for parity RAID (3+1 for RAID 5, 6+2 for RAID 6) will require only 8 disk
I/Os. The disk I/O cost of RAID 1 in this case is 50% more than either form of parity RAID.

2.3 RAID on Physical Drives: Reads

Read performance (uncached) requires one disk I/O per host read, whether random or
sequential. RAID 5 and RAID 6 store less redundant data than RAID 1, and thus require shorter
seeks for random reads if the same number of physical disks are used. Storage efficiency—the
ratio of usable data to raw data—is a useful approximation of the relative cost of seeks between
the different RAID levels.

3 3PAR’s Improved Implementation of RAID

3PAR InServ Storage Servers embody several enhancements over conventional RAID arrays. By
making more effective use of all drive resources in the array, these enhancements allow higher
performance with less hardware, which in turn leads to cost reduction.

3.1 Chunklet-based RAID

The 3PAR InForm Operating System divides physical drives into 256-MB chunklets, each of
which can be viewed as its own small disk. RAID groups are constructed from chunklets on
separate drives. Several of these RAID groups are then combined into a Logical Disk (LD), with
LD data striped over the RAID groups. LDs using RAID groups from as many physical drives as
possible are then concatenated to form Virtual Volumes (VVs). By widely striping each VV over
chunklets on many physical drives, much higher performance is achieved than if RAID groups
were constructed from whole disks as is done in traditional storage arrays.

3.1.1 Wide Striping for Performance

In a traditional storage array, small volumes either suffer from poor performance by using few
drives or waste expensive resources by using more drives than required for capacity in order to
obtain sufficient performance.

On an InServ, even modest-sized volumes will be widely striped using chunklets spread over all
drives of the same type. Wide striping provides the full performance capabilities of the array to
small volumes without provisioning excess capacity and without creating hot spots on a subset of
physical drives. (Figure 1) Other chunklets on the drives are available for other volumes.

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© 2010 3PAR Inc. All rights reserved. 3PAR, the 3PAR logo, Serving Information, InServ, InForm, InSpire, and Thin Built In are all
trademarks or registered trademarks of 3PAR Inc. All other trademarks and registered trademarks are the property of their
respective owners.




About 3PAR

3PAR® (NYSE: PAR) is the leading global provider of utility storage, a category of highly
virtualized, dynamically tiered, multi-tenant storage arrays built for public and private cloud
computing. Our virtualized storage platform was built from the ground up to be agile and efficient
and to eliminate the limitations of traditional storage arrays for utility infrastructures. As a pioneer
of thin provisioning and other storage virtualization technologies, we design our products to
reduce power consumption to help companies meet their green computing initiatives, and to cut
storage total cost of ownership. 3PAR customers have used our self-managing, efficient, and
adaptable utility storage systems to reduce administration time and provisioning complexity, to
improve server and storage utilization, and to scale and adapt flexibly in response to continuous
growth and changing business needs. For more information, visit the 3PAR Website at:
www.3PAR.com.

http://www.3par.com/�
http://3par.com/products/hardware.html�
http://3par.com/products/hardware.html�
http://www.3par.com/solutions/cloud_computing.html�
http://www.3par.com/solutions/cloud_computing.html�
http://www.3par.com/products.html�
http://www.3par.com/�

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