HP Smart Array Controller technology HP Smart Array Controller technology technology brief, 3 technology brief, 3 edition edition Abstract.............................. 3 Introduction............................3 Storage trends............................. 3 Meeting data storage requirements......................4 High performance..........................4 PCI Express technology........................4 SAS/SATA technology ........................5 SAS-2 standard ..........................
Recovering data from battery-backed cache .................. 19 Selection criteria for battery-backed cache ..................19 Types of batteries ........................19 Battery replacement ........................20 Alternatives to battery replacement ....................20 Flash-backed write cache ........................ 20 FBWC architecture ........................21 FBWC cache ..........................22 Super-capacitor..........................
Abstract This technology brief describes specific functions of the HP Smart Array controller family and explains how Smart Array technology meets administrators’ requirements for capacity growth, high performance, data availability, and manageability. Introduction In today’s networking environments, administrators face difficult online data storage problems and ever-increasing performance demands.
Meeting data storage requirements The HP Smart Array controller family has an advanced intelligent architecture developed with a feature set that specifically addresses today’s network data storage requirements: • Capacity growth — Administrators can expand server storage capacity while the server is operating.
Figure 1. PCIe data transfer rates Lane 1 Send Lane 1 Send Max. bandwidth Total (Send or receive) (Send and receive) Link Lane 1 Receive Lane 1 Receive size PCIe 1.0 PCIe 2.0 PCIe 1.0 PCIe 2.0 Source Source 250 MB/s 500 MB/s 500 MB/s 1 GB/s...
• SAS wide port operations — Wide ports contain four single lane (1x) SAS connectors and the cabling bundles all four lanes together. SAS wide ports allow balanced SAS traffic distribution across the links for enhanced performance. In addition, wide ports provide redundancy by tolerating up to three physical link failures while maintaining the ability to communicate with the disk drives.
Mini SAS 4x cable connectors and receptacles Mini SAS 4x connectors and receptacles (Figure 2) are replacing SAS 4x connectors and receptacles in present generation Smart Array controllers. The ground pins in Mini SAS connectors can be used for power in active cables. Figure 2.
Cache module benefits With advanced read-ahead and write-back caching capabilities, the Smart Array controller cache module produces significant performance improvements for I/O operations. Read-ahead caching The HP Smart Array controller family uses an intelligent read-ahead algorithm that can anticipate data needs and reduce wait time.
Balanced cache size Smart Array controllers allow administrators to adjust how the cache is distributed for write-back and read-ahead operations. Administrators can configure the cache module for optimal performance for any storage need. The default setting for most present generation Smart Array controllers configures the cache for 75 percent write-back operations and 25 percent read-ahead operations, but these default settings can vary by controller.
Striping across arrays RAID 50 and 60 methods stripe the data across multiple RAID/JBOD sets with different levels of parity. These nested RAID types allow users to configure arrays across HP Modular Smart Arrays (MSAs). RAID 50 (RAID 5+0) is a nested RAID method that uses RAID 0 block-level striping across RAID 5 arrays with distributed parity.
Smart Array performance This section presents results of HP testing for sequential read/write performance between Smart Array controller P411, announced in April 2009, and the previous generation P800. The charts in Figures 3, 4, and 5 compare the maximum performance for each Smart Array controller across the queue depth in each data range.
The performance gains shown by the Smart Array P411 in RAID 5 and 6 sequential writes (Figures 4 and 5) result from improvements to the Smart Array firmware and hardware. The RAID 5 maximum sequential read/write performance test results shown in Figure 4 indicate significant performance gains for the Smart Array P411 over the previous generation P800 controller.
Maximum sequential read/write performance for the Smart Array P800 and P411 controllers Figure 5. in a RAID 6 environment RAID-6, Maximum performance 2500 2000 1500 1000 64KB 512KB 64KB 128KB 256KB 512KB READ READ READ READ WRITE WRITE WRITE WRITE WRITE P411, 512MB, fw: 2.50, RAID 6 (256KB), D2700, 14-146GB SFF 6Gb SAS 15K, DL380-G6 P800, 512MB, fw: 7.00, RAID 6 (256KB), MSA70, 14-146GB SFF 3Gb SAS 15K, DL380-G5...
Data availability Smart Array controllers support online array expansion, logical drive extension, stripe size migration, and RAID migration. These technologies protect data and allow network administrators to modify the array without interrupting user access. Smart Array controllers can monitor I/O activity, track key parameters, predict potential problems, take corrective actions, provide automatic recovery, and deliver full fault management to protect against downtime.
Recommended stripe sizes Table 4. Type of server application Suggested stripe size change Mixed read/write Accept default value Mainly sequential read (such as audio/video Larger stripe sizes applications) Mainly write (such as image manipulation Smaller stripes for RAID 5, RAID 6 applications) Larger stripes for RAID 0, RAID 1, RAID 1+0 NOTE:...
Drive roaming HP Smart Array controllers support drive roaming, which allows administrators to move disk drives and arrays while maintaining data availability. Drive roaming allows administrators to move one or more disk drives that are members of a configured logical drive to a different bay position as long as the new bay position is accessible by the same controller.
HP worked with the disk drive industry to help develop a diagnostic and failure prediction capability known as Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T.). Over the years, as S.M.A.R.T. matured, HP used both M&P and S.M.A.R.T. to support disk drive failure prediction technology for Pre-Failure Warranty disk drive replacement.
If an active drive fails during system operation, the controller automatically begins rebuilding each fault-tolerant logical drive onto the online spare; no administrator action is required. Once the rebuild operation is complete, the system is fully fault-tolerant once again. The failed drive can be replaced at a convenient time.
Recovering data from battery-backed cache If an unexpected server shutdown occurs while data is held in BBWC, Smart Array controllers automatically signal the memory chips to enter a self-refresh state and the controller initiates battery power, or system auxiliary power if present. An amber LED, available either on the cache module or battery pack, begins flashing to indicate that data is trapped in the cache.
The HP 650 mAh P-Series battery has the same form factor as previous versions and extends battery life up to 48 hours before recharging is necessary. Battery replacement HP Smart Array controllers include serviceable battery packs that allow tool-free battery pack replacement with no need to replace either the Smart Array controller or the detachable cache module.
Figure 7. HP flash-backed write-cache and Super-cap power supply The FBWC uses NAND flash devices to retain cache data and super-capacitors (Super-caps) instead of batteries to provide power during a power loss. The FBWC offers significant advantages over the HP Battery-backed write-cache (BBWC) system. Since the FBWC writes the contents of memory to flash devices, there is no longer a 48 hour battery life limitation and the data will be posted to the disk drive on the next power up.
Figure 8. FBWC block diagram Super-cap NAND Flash NAND Flash Side band control In off-module pack connecting to 4b 33MHz 4b 33MHz 4b 33MHz 4b 33MHz signals cache module FPGA PROM DRAM DRAM DRAM 133 MHZ DDR IF Command & address Register Cache module Cache module...
Recovering data from the flash-backed cache When system power is present, the FPGA on FBWC is in its idle state. In the idle state, the FPGA simply monitors the voltage statuses, the resets, and the control signals managed by the Smart Array controller.
Storage support and pathway redundancy HP Smart Array controllers support solid state drives, Native Command Queuing and Dual Domain providing increased performance and redundancy on the storage network. Smart Array controllers continue to support tape back up devices. Solid state drives HP has introduced the second generation of solid state drives (SSD) for ProLiant servers.
Tape device support Smart Array controllers support tape back-up devices. The One Button Disaster Recovery (OBDR) ProLiant server/controller compatibility matrix for currently shipping HP products is available at www.hp.com/go/obdr. Smart Array Advanced Pack HP Smart Array Advanced Pack (SAAP) firmware provides advanced functionality within Smart Array controllers.
Storage management To improve data storage management, HP Smart Array controllers include built-in intelligence that makes it easier for administrators to configure, modify, expand, manage, and monitor storage. HP provides five utilities for managing an array on a Smart Array controller: •...
Utility features ORCA CPQONLIN Setting stripe size Migrating RAID level or stripe size Configuring controller settings Expanding an array Creating multiple logical drives per array Setting of boot controller Array Configuration Utility The ACU is a browser-based graphical application that helps configure Smart Array controllers. The ACU is also supported on the HP MSA family of entry-level SAN products.
Performance monitoring HP SIM gives administrators a window to look at low-level performance characteristics of Smart Array controllers in the environment. It monitors three basic Smart Array controller performance parameters for proactive storage subsystem management: • I/O commands per second •...
Appendix A: Capacity growth technologies The Smart Array controller family includes a standard toolset that administrators can use to configure array controllers, expand an existing array configuration by adding disk drives, or reconfigure an array by extending logical drive sizes. Before this innovation, expanding the storage capacity attached to an array controller required a time-consuming backup-reconfigure-restore cycle.
The ACU allows administrators to set the priority of array expansion operations. A high-priority setting prioritizes the array expansion operation over I/O requests. A low-priority setting is the ACU default setting and gives I/O commands precedence over array expansion. During idle time, when no I/O commands are active, the array expansion operation runs at full speed regardless of the priority setting.
Logical drive extension Logical drive extension increases the storage space of a logical drive (Figure A3). During this process, an administrator adds new storage space to an existing logical drive on the same array. An administrator may have gained this new storage space either by array expansion or by deleting another logical drive on the same array.
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