HP Smart Array Controller technology, 4th edition

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HP Smart Array controller technology

Technology brief, 4

edition

Introduction......................................................................................................................................... 2

Smart Array performance factors ........................................................................................................... 2

Smart Array processing engine .......................................................................................................... 2

Hardware tuning.............................................................................................................................. 3

Cache module performance benefits................................................................................................... 3

RAID performance enhancements........................................................................................................... 5

Background RAID creation ................................................................................................................ 5

RAID 5 and RAID 6 read-modify-write................................................................................................. 5

Striping across arrays....................................................................................................................... 5

RAID 1 load balancing ..................................................................................................................... 5

Data availability .................................................................................................................................. 5

Adjusting strip size with the Array Configuration Utility (ACU) ............................................................... 6

RAID migration with ACU.................................................................................................................. 6

Drive roaming.................................................................................................................................. 6

Mirror splitting and recombining with the ACU .................................................................................... 6

Online drive flash............................................................................................................................. 7

Recovery ROM ................................................................................................................................ 7

Pre-Failure Warranty using S.M.A.R.T technology ................................................................................ 7

Automatic data recovery with rapid rebuild technology ........................................................................ 7

Online spare ................................................................................................................................... 8

Dynamic sector repair....................................................................................................................... 8

ECC protection ................................................................................................................................ 8

Write caches ................................................................................................................................... 8

Software RAID ............................................................................................................................... 12

Zero Memory RAID ........................................................................................................................ 12

Smart Array Advanced Pack ............................................................................................................... 12

RAID 6.......................................................................................................................................... 13

RAID 60........................................................................................................................................ 13

Advanced Capacity Expansion (ACE)...............................................................................................13

Mirror splitting and recombining...................................................................................................... 13

Drive erase.................................................................................................................................... 13

Storage pathway redundancy.......................................................................................................... 14

Video on Demand (VOD) ................................................................................................................ 14

Storage management ......................................................................................................................... 14

Array Configuration Utility............................................................................................................... 15

Option ROM Configuration for Arrays.............................................................................................. 16

CPQONLIN................................................................................................................................... 16

HP Systems Insight Manager............................................................................................................ 16

Array Diagnostics Utility.................................................................................................................. 16

Summary .......................................................................................................................................... 17

For more information.......................................................................................................................... 18

Call to action .................................................................................................................................... 19

Summary of content (19 pages)

PAGE 1
HP Smart Array controller technology Technology brief, 4th edition Introduction ......................................................................................................................................... 2 Smart Array performance factors ........................................................................................................... 2 Smart Array processing engine ..........................................................................................................
PAGE 2
Introduction In 1989, HP (then Compaq) was the first company to introduce RAID subsystems in the network server marketplace. Today, RAID is an industry-standard technology used for most online network data storage. Our Smart Array controllers support RAID levels 0, 1, 1+0, 5, 6, 50, and 60. HP engineers continue to enhance Smart Array performance, expansion, migration, and data availability capabilities. We provide administrators with tools for Smart Array configuration, storage management, and diagnostics.
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The Smart Array processing engine is responsible for processing all operations, but its capabilities are particularly critical to complex RAID functions such as write operations. Both RAID 5 and RAID 6 use mathematical XOR (Exclusive or) operations to calculate the parity data written to the drive array for data recovery. The processing engine is essential for high performance operations at these RAID levels, particularly write performance.
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The controller disables read-ahead when it detects non-sequential read activity. HP Smart Array controller adaptive read-ahead caching eliminates issues with fixed read-ahead schemes that increase sequential read performance but degrade random read performance. Write-back caching HP Smart Array controllers use a write-back caching scheme that lets host applications continue without waiting for write operations to complete to the disk.
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RAID performance enhancements Smart Array controllers use several enhancements to increase RAID performance. Background RAID creation When you create a RAID 1, RAID 5, or RAID 6 logical drive, the Smart Array controller must build the logical drive within the array and initialize the parity before enabling certain advanced performance techniques. Parity initialization takes several hours to complete. The time it takes depends on the size of the logical drive and the load on the controller.
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take corrective actions, provide automatic recovery, and deliver full fault management to protect against downtime. Adjusting strip size with the Array Configuration Utility (ACU) You can change the strip size of a logical drive, a process called strip-size migration, without any downtime by using the Array Configuration Utility, a browser-based graphical application that helps configure Smart Array controllers.
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You can also recombine a split-mirrored array with the ACU. When you recombine a split-mirrored array, you lose access to all data on the second array. The Smart Array Advanced Pack (SAAP) may be required to use the mirror splitting and recombining functions. For support information regarding mirror splitting on specific controllers, see the controller QuickSpecs. NOTE: You must split or re-mirror arrays when the server is offline and operating in the standard configuration mode of ACU.
PAGE 8
The present generation of Smart Array controllers includes rapid rebuild technology for accelerating the rebuild process. Faster rebuild time helps restore logical drives to full fault tolerance before a subsequent drive failure can occur, reducing the risk of data lass. Generally, a rebuild operation requires approximately 15 to 30 seconds per gigabyte for RAID 5 or RAID 6.
PAGE 9
auxiliary power if available. An amber LED on the cache module or battery pack begins flashing to indicate that data is in the cache. Smart Array controllers automatically write this data to disk when the system powers up. The posted-write data in the cache will be lost if the batteries drain completely before the system powers up. The batteries automatically recharge when the system has power. Battery recharge takes between 30 minutes and 2 hours, depending on the remaining capacity level.
PAGE 10
If it is not possible or desirable to replace the batteries, you have three options to disable write-back cache and avoid losing critical data:  Use the ACU to adjust the read-and-write cache ratio to 100 percent read cache.  Use the ACU to disable the array accelerator for each logical drive, which disables both read-ahead and write-back cache.  Replace an existing RAID controller with a newer Smart Array controller model. NOTE: If the write cache is off, some write performance degradation may occur.
PAGE 11
Figure 1. FBWC block diagram NAND Flash Side band control signals 4b 33MHz 4b 33MHz Data FPGA Command & address Super-cap NAND Flash In off-module pack connecting to cache module PROM DRAM 8X DRAM 8X DRAM 8X 133 MHZ DDR IF Register Cache module System board 400 MHZ DDR IF Cache dirty N* Reset N Reg reset N RoC TWI** * Cache tracks written over are “dirty.
PAGE 12
The Smart Array controller moves the data from the cache to the DRAMs, verifies that the data is correct, and then transfers it to the disk drives. Software RAID Today’s operating systems offer basic support for RAID disks (called software RAID) to create and manage logical drives that do not contain the OS. Software RAID can require a significant amount of the server’s resources and harm performance.
PAGE 13
RAID 6 RAID 6 protects against failure of any two drives. It requires a minimum of four drives, but only two are available for data. RAID 6 can tolerate multiple simultaneous drive failures without downtime or data loss. It is ideal for applications requiring large logical volumes, because it can safely protect a single volume of up to 56 disk drives. RAID 6 also offers lower implementation costs and greater usable capacity per U than RAID 1.
PAGE 14
Storage pathway redundancy Dual Domain support for SAS creates redundant pathways from servers to storage devices. These redundant paths reduce or eliminate single points of failure within the storage network and increase data availability. Dual Domain SAS implementations can tolerate HBA failure, external cable failure, expander failure, or failure in a spanned disk (JBOD).
PAGE 15
executables. Starting with version 8.28.13.0, ACU Scripting is a stand-alone application that is distributed with the ACU CLI application. The new ACU scripting executable (hpacuscripting) replaces the former executable (cpqacuxe) in all scripts.
PAGE 16
The ACU also contains a command line interface (ACU-CLI), offering a quicker way to deploy multiple servers by automating creation of arrays and logical drives. Option ROM Configuration for Arrays ORCA is an alternative method of viewing, creating, and deleting multiple arrays and logical drives during system power up. Although ORCA performs all array configuration tasks, it works best with simpler configurations. We recommend the ACU for more advanced array configurations.
PAGE 17
Summary HP Smart Array controllers are powerful I/O solutions for today’s most demanding storage requirements. Our controllers provide solutions for all four primary data storage requirements:  Capacity growth  High performance  Data availability  Manageability HP is the only server provider with a seamless storage solution set that spans the range from embedded Smart Array controllers in servers to plug-in PCI Smart Array controllers to SAN-attached Modular Smart Arrays storage.
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For more information Resource description Web address Server drive technology http://h20000.www2.hp.com/bc/docs/support/SupportMan ual/c01071496/c01071496.pdf HP Smart Array controllers www.hp.com/products/smartarray HP disk drive products www.hp.com/products/harddiskdrives HP Modular Smart Array external storage systems www.hp.com/go/msa HP ProLiant servers www.hp.com/go/proliant HP Smart Array Controllers and basic RAID performance factors http://h20000.www2.hp.
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Call to action Send comments about this paper to TechCom@HP.com Follow us on Twitter: http://twitter.com/ISSGeekAtHP © Copyright 2010 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty.