Ultra320 SCSI technology in HP Smart Array controllers

Transcription

1 Ultra320 SCSI technology in HP Smart Array controllers technology brief Abstract... 2 Introduction... 2 Common features...2 Ultra320 SCSI technology... 2 Data compatibility... 2 Availability... 2 Fault prevention... 3 Fault recovery... 3 Performance monitoring... 3 HP Smart Array 6402/6404 controllers... 3 Smart Array 6402 Controller... 4 Smart Array 6404 Controller... 4 Double Data Rate battery-backed write cache module... 5 HP RAID Advanced Data Guarding... 5 Operating system compatibility... 7 Typical applications... 7 Smart Array 641/642 controllers... 7 Smart Array 641 Controller... 7 Smart Array 642 Controller... 8 Battery-backed write cache enabler... 8 Operating system compatibility... 9 Typical applications... 9 Ultra320 SCSI technology Performance enhancements Double transition clocking Packetization and QAS Read and write data streaming Flow control Pre-compensation and training Controller compatibility matrix Conclusion For more information Call to action... 13

2 Abstract This technology brief describes the latest line of Ultra320 SCSI Smart Array controllers from HP, including their performance features, modular design, and battery-backed write cache architecture. Introduction The HP family of Smart Array controllers continues to provide customers with innovative solutions that meet their constant need for faster and more reliable access to data and maximize their return on investment. HP's latest line of Smart Array controllers uses Ultra320 SCSI technology to increase the maximum bandwidth of the SCSI interface to 320 MB/s per channel through a 64-bit, 133-MHz PCI-X connector. These controllers are backward compatible with Ultra2 and Ultra160 SCSI interface devices. The Smart Array 6402 controller and the Smart Array 6404 controller offer maximum performance, flexibility, and reliable data protection for HP ProLiant servers. These controllers deliver enterpriseclass performance through a Double Data Rate (DDR) battery-backed write cache (BBWC) architecture and a new Redundant Array of Independent Disks (RAID) XOR engine. They provide flexibility through two Error-Correction Code (ECC)-protected cache memory module options: 128 MB and 256 MB. They provide reliable data protection through their support for HP RAID Advanced Data Guarding, which has higher fault tolerance than RAID 5 and lower implementation cost than RAID 1. The Smart Array 641 and 642 controllers provide ProLiant DL and ML servers with entry-level hardware RAID protection. These controllers ship standard with 64 MB DDR-RAM. They are upgradeable to 128 MB with a transportable 64-MB BBWC Enabler that takes entry-level RAID data protection to a new level. This paper begins with a description of the common features of the Smart Array 6402, 6404, 641, and 642 controllers. Then it describes the technologies incorporated in each controller. Common features The Smart Array 6402, 6404, 641, and 642 controllers share the following features and functionalities. Ultra320 SCSI technology The Smart Array controllers use Ultra320 SCSI to provide a bandwidth of 320 MB/s per channel. See the "Ultra320 SCSI" section for more information. Data compatibility Each Smart Array controller provides complete data compatibility with previous-generation Smart Array controllers. This compatibility makes it easy to upgrade array controllers by swapping controllers, and makes it easy to migrate data from server to server by moving data drives to new controllers. Availability The following features increase server uptime by providing advanced storage functionality: Online RAID level migration (between any RAID levels) Online capacity expansion Logical drive capacity extension Global online spare Pre-Failure Warranty 2

3 Fault prevention The following features detect possible hardware failures before they occur so that administrators can take preventive action: Self Monitoring Analysis and Reporting Technology (S.M.A.R.T.), first developed at HP, detects an impending hard disk failure before it occurs, allowing replacement of the drive before it fails. Drive Parameter Tracking monitors operational parameters of disk drives to enable failure prediction and notification to the administrator. Dynamic Sector Repairing continually performs background surface scans of the disk drives during inactive periods and automatically remaps bad sectors to ensure data integrity. Environment tracking monitors the external storage system. Both pre-failure and failure alerts can be sent to HP's Insight Manager, HP OpenView Operations, and HP OpenView Network Node Manager, as well as industry leading management solutions. Online web-based tools for real-time monitoring of the controllers health through HP Insight Management Agents. Fault recovery The following features minimize downtime, reconstruct data, and facilitate a quick recovery from a drive or controller failure: Recovery ROM This unique redundancy feature protects against ROM image corruption during firmware flashing. A new version of firmware can be flashed to the ROM while the controller maintains the last known working version of firmware. If the firmware becomes corrupt during the flash process, the controller will revert to the previous version of firmware and continue operating. On-Line Spares The controllers support On-Line Spare drives. If a drive fails, data on the failed drive is reconstructed automatically on a spare drive. Note that On-Line Spares can only be used with RAID level 1, 1+0, 5 and RAID ADG. Performance monitoring The ProLiant Essentials Performance Management Pack (PMP) supports proactive performance management of Smart Array controllers: PMP analyzes the workload placed on the Smart Array controller and all hard drives and SCSI buses attached to the controller, and reports the performance status to HP s Insight Manager. Performance alerts can be sent to HP s Insight Manager. HP Smart Array 6402/6404 controllers The dual-channel Smart Array 6402 controller and quad-channel Smart Array 6404 controller are uniquely designed, high-performance array controllers that provide maximum flexibility and reliable data protection for PCI-X based ProLiant servers. The Smart Array 6402 and 6404 controllers are ideal for workgroup and departmental servers. These controllers provide increased performance by using a new RAID XOR engine and a 266-MHz DDR battery-backed write cache architecture. Both controllers support RAID ADG, which is a fault-tolerant storage solution for customers that need a lower-cost method of protecting enterprise data than using RAID 1 arrays (see the "HP RAID Advanced Data Guarding" section). The remainder of this section describes the technical features and capabilities of the Smart Array 6402 and 6404 controllers and the DDR BBWC module. It also explains RAID ADG, lists the operating systems (OSs) that support the controllers, and describes some typical applications. 3

4 Smart Array 6402 Controller Figure 1 illustrates the major components of the dual-channel Smart Array 6402 (SA-6402) controller. Each channel (A1 and A2) is shared by one external port and one internal port. Only one port on each channel can be used at a time. The SA-6402 can support up to 28 drives with a total capacity of 4 terabytes (TB) (28 drives x 146 GB/drive). It can also support up to 32 logical drives with up to 2 TB per logical drive. Figure 1. Dual channel Smart Array 6402 Controller Smart Array 6404 Controller The Smart Array 6404 Controller (SA-6404) is the SA-6402 with a 2-channel Ultra320 SCSI expansion module (see Figure 2) connected to the expansion slot. Because the expansion module is itself a controller, the SA-6404 is actually two 2-channel controllers sharing one PCI-X connector. This dual (or twin) controller configuration makes the SA-6404 the industry's first array controller with multiple processors. Figure 2. Dual-channel Smart Array 6404 Controller 4

5 During POST, the Ultra320 SCSI Smart Array controllers initialize the drive configurations and check for failures and missing drives. Users have the option to use Option ROM Configuration for Arrays (ORCA) to create, delete, or change the configuration. The dual controller is displayed in both Insight Manager and the HP Array Configuration Utility (ACU) as two separate entities in one slot. In these utilities, the slot number label for the expansion module has a lowercase "b" suffix, while the slot number label for the main controller does not have a suffix. Double Data Rate battery-backed write cache module The SA-6402 and SA-6404 controllers offer a 128-MB ECC-protected cache BBWC module and an optional 256-MB BBWC module. In the event of power failure, server hardware failure, or controller failure, the 128-MB BBWC module protects data up to four days and the 256-MB BBWC module protects data for up to three days assuming each module stays attached to the controller. This is enough time for system administrators to recover the data and preserve the integrity of business-critical information. The BBWC design includes redundant and replaceable batteries for greater cache protection (Figure 3) Figure 3. The removable battery-backed write cache module consists of a cache board and a battery pack. WARNING: due to the risk of serious injury, refer to HP Smart Array 6400 Series Controllers User Guide before installing or removing any item that contains a battery pack. HP RAID Advanced Data Guarding The SA-6402 and SA-6404 controllers support the following RAID levels: HP RAID Advanced Data Guarding (RAID ADG) RAID 5 (distributed data guarding) RAID 1+0 (striping and mirroring) RAID 1 (mirroring) RAID 0 (striping) 5

6 In a RAID 0 implementation, a file is split into blocks and each block is striped across all the drives in the array. Striping (spreading) data over multiple disk drives improves performance. RAID 1, 1+0, and 5 implementations are typically used for arrays that store enterprise data. RAID 1 and 1+0 provide high performance and fault tolerance, but they are more expensive to implement than RAID 5 because they double the number of drives required for the same usable capacity. RAID 5 is recommended for arrays of up to 14 hard drives. As shown in Figure 4, RAID 5 calculates parity information for each stripe of data, distributes the parity data across all drives in the array, and allows simultaneous write operations. The parity information for each stripe of data is placed on a different drive than the drive used to store the stripe of data. The parity information for all data stripes occupies the equivalent capacity of one drive in the array. Overall, RAID 5 provides good performance, but it can only withstand the loss of one drive without failure of the array. RAID ADG is an extension of RAID 5 that protects against the simultaneous failure of two drives in the array without downtime or data loss. RAID ADG stripes data and two sets of parity information across all drives in the array. The additional set of parity improves the fault tolerance of the array, but it results in lower write performance. RAID ADG performance, like that of other RAID levels, depends on the nature of the application. The two parity sets occupy the equivalent capacity of two drives in the array. Figure 4. Comparison of RAID 5 and HP RAID ADG RAID 5 HP RAID Advanced Data Guarding Requires a minimum of three drives. One set of parity data (Pn) is distributed across all drives. This protects against the failure of any one drive in an array. Requires a minimum of four drives. Two sets of parity data (Pn and Qn) are distributed across all drives. This protects against the failure of two drives in an array. Provides higher fault tolerance than RAID 5. To choose the optimum RAID level for data protection in large arrays, customers should consider a variety of factors, including: Fault tolerance (based on availability requirements) Cost effectiveness (based on storage efficiency or cost per gigabyte of usable capacity) Performance (based on application requirements) To determine which RAID level provides the best solution, customers can use the decision chart in the technology brief, HP RAID Advanced Data Guarding: A Cost-effective, Fault-tolerant Solution (document number TC020604TB). 6

7 Operating system compatibility The SA-6402 and SA-6404 controllers are supported by the following OSs: Microsoft Windows NT 4.0, 2000 Windows Server 2003 Novell NetWare 5.x, 6, and 6.5 SCO UnixWare 7.1.1, SCO Unix 5.0.6a, Sun Solaris 8 x86 and Sun Solaris 9 x86 Red Hat 2.1 Advanced Server Red Hat 7.2 Professional, Red Hat 7.3 Professional, Red Hat 8.0 Professional SuSE SLES 7 United Linux 1.0 Typical applications The dual-channel SA-6402 controller allows customers to use one internal channel and one external channel. Alternatively, they can use the two internal channels or the two external channels. The quadchannel SA-6404 controller adds two external channels, supporting configurations with up to four external channels, one internal and up to three external channels, or two internal and up to two external channels. Consistent with HP's low voltage differential (LVD) strategy, the SA-6402 and SA-6404 controllers can be used to mix and match Ultra320, Ultra160, and Ultra2 SCSI devices on the same Ultra320 SCSI bus. Smart Array 641/642 controllers The Smart Array 641 (SA-641) and Smart Array 642 (SA-642) controllers provide ProLiant DL and ML servers with entry-level hardware RAID protection for OS and log files. The SA-641 and SA-642 controllers support RAID 0, 1, 1+0, and 5; they do not support RAID ADG. The SA-641 and SA-642 controllers have 64 MB of DDR DRAM and they are upgradeable to 128 MB with a 64-MB BBWC Enabler. Both controllers are backward compatible with Ultra2 and Ultra160 SCSI drives, which protects customers investment in those storage drives. Smart Array 641 Controller The SA-641 is a 64-bit, 133-MHz PCI X, single-channel array controller that provides entry-level hardware-based fault tolerance (see Figure 5). The SA-641 has a single, internal Ultra320 SCSI channel that allows customers to configure up to six internal disk drives with a total capacity up to GB per PCI slot. 7

8 Figure 5. Smart Array 641 Controller Smart Array 642 Controller The SA-642 is a 64-bit, 133-MHz PCI-X, dual-channel PCI-X array controller (see Figure 6). The SA- 642 has one internal and one external Ultra320 SCSI channel; both channels can be used simultaneously. Using both channels, customers can configure up to 20 disk drives (six internal, and fourteen external) with a total storage capacity of up to 2.9 TB per PCI slot. Figure 6. Board components of the Smart Array 642 Controller Battery-backed write cache enabler The SA-641 and SA-642 controllers can be used with the optional 64-MB BBWC Enabler (Figure 7) to increase the total controller memory to 128 MB and improve controller performance. The cache module is transportable, and it can be interchanged between SA-641 and SA-642 controllers in supported servers. The transportability of the cache module protects data in the write cache from unexpected power loss, system board failure, or controller board failure. Data retained in the write cache will be protected for up to 72 hours, allowing customers time to restore power or transport the 8

9 cache module to a functioning SA-641 or SA-642 array controller. For example, if an SA-641 with the 64-MB BBWC Enabler is installed in a supported server that experiences a system board failure, the BBWC Enabler can be moved to a SA-642 controller in a different server. Figure 7. Optional 64-MB BBWC Enabler Operating system compatibility The SA-641 and SA-642 controllers are supported by the following OSs: Microsoft Windows NT 4.0, 2000 Windows Server 2003 Novell NetWare 5.x, 6 SCO UnixWare 7.1.1, SCO Unix 5.0.5, SCO OpenUnix 8 Red Hat 2.1 Advanced Server Red Hat 8.0 Professional Red Hat 7.3 Professional SuSE SLES 7 IBM OS/2 WARP Server for e-business United Linux 1.0 Typical applications The SA-641 and SA-642 controllers are ideal for customers who need data protection for OS and log files to increase server uptime. Higher performance can be achieved with the 64-MB BBWC Enabler. 9

10 Ultra320 SCSI technology Since 1981, there have been seven generations of the SCSI protocol. Each new generation has doubled the performance of the previous one. The Ultra320 SCSI protocol is the latest generation in the SCSI standard, providing a 16-bit, low-voltage differential interface transferring data at 320 MB/s per channel (Ultra320 SCSI). The higher performance of Ultra320 SCSI is made possible by the implementation of several enhancements to the specification (see following page). Ultra320 SCSI is backward compatible with low-voltage Ultra2 SCSI and Ultra160 SCSI (Figure 8). When an Ultra320 Smart Array controller communicates with a SCSI device from a previous generation, the SCSI device will negotiate at its maximum speed. This backward compatibility aids integration of Ultra320 SCSI into existing systems and protects customers investment in older SCSI devices. Figure 8. Bandwidths of seven generations of the SCSI protocol Ultra320 SCSI provides the performance and scalability that mid-tier and high-tier servers require. It allows up to 15 SCSI devices on a single channel or up to 30 devices on dual channels. Ultra320 SCSI Smart Array controllers achieve the highest performance when used in systems with 64-bit, 133- MHz PCI-X slots (see Figure 9). PCI 64/66 is a bottleneck to Ultra320 SCSI (and 2-channel Ultra160 SCSI) because most PCI buses have multiple segments (slots) that share the bandwidth of the bus. Figure 9. PCI-X 133 meets the bandwidth requirement for dual-channel Ultra320 SCSI performance. 10

11 Performance enhancements Ultra 320 SCSI operates at twice the clock frequency of Ultra160 SCSI. Ultra320 SCSI uses double transition clocking, packetization and quick arbitration and selection (QAS), read and write data streaming, and flow control to improve data throughput and bus utilization. Ultra320 SCSI also introduces pre-compensation and training technologies that protect against data corruption at higher transfer rates. 1 Double transition clocking Ultra320 SCSI uses double transition clocking to trigger data transfer on both the rising and falling edges of the bus clock signal. In addition, Ultra320 SCSI operates at 80 MHz twice the frequency of Ultra 160 SCSI to increase bandwidth to 320 MB/s per channel. Packetization and QAS Packetization is a technique that combines some of the phases involving command request and data transfer. For example, in traditional SCSI, several different types of information, such as commands, data, and status messages, are sent over the bus separately. Packetization groups all of this information together and sends it as a single entity. This eliminates some of the bus cycles required for individual transfers in previous versions of SCSI. QAS speeds up bus arbitration and device selection by eliminating the bus free phase and reducing the number of times arbitration must occur. QAS allows another device to grab the bus without arbitration once the previous initiator and target devices disconnect. Theoretically, packetization and QAS can each increase the performance of Ultra320 SCSI by 10 to 15 percent (for a total gain of 20 to 30 percent). Read and write data streaming Another innovation of packetized SCSI is the introduction of a read and write data streaming procedure that speeds the transmission of data packets by simplifying the request/acknowledge process (the core of handshaking). A data stream is all data transmitted through a communications line in a single read or write operation. Read data streaming minimizes the overhead of data transfer by allowing the target to send one data stream LUN Q-TAG (LQ) packet followed by multiple data packets. Faster read data transmission also boosts performance of write data streaming because the bus turn-around delay (from data in to data out) does not occur between each LQ and data packet. Flow control To improve drive performance, some disk manufacturers have implemented technology called prefetching. Using statistical analysis of memory access patterns, pre-fetching enables the disk cache to load data that it anticipates will be requested. Usually, this means loading more data from the disk than was requested. Ultra320 SCSI includes a new technology called flow control that allows the initiator to optimize its pre-fetching of data during writes and to flush data first-in, first-outs (FIFOs) during reads. The target device indicates when the last packet of a data stream will be transferred, which allows the initiator to terminate the data pre-fetch or begin flushing data FIFOs sooner than was previously possible. Pre-compensation and training Ultra320 SCSI also introduced two new technologies pre-compensation and training to minimize the negative impact of attenuation and signal skew (slight signal delays from one wire trace to the next) on signal integrity. 1 For more information about these features, please refer to the technology brief Ultra320 SCSI Maintains SCSI Prevalence, document number TC021006TB. 11

12 Controller compatibility matrix Table 1 lists the ProLiant DL and ML servers that support the new line of HP Ultra320 SCSI Smart Array Controllers. For updated information, please refer to the Server Compatibility matrix at ftp://ftp.compaq.com/pub/products/servers/proliantstorage/arraycontrollers/compatabilitymatrix.pdf. Table 1. Hardware compatibility matrix Conclusion The HP Smart Array family consistently delivers reliable storage protection, performance, and management from generation to generation. HP's latest line of Smart Array controllers use Ultra320 SCSI technology to increase the maximum bandwidth of the SCSI interface to 320 MB/s per channel, plus they maintain backward compatibility with Ultra2 and Ultra160 SCSI interface speeds. These Smart Array controllers meet a range of customer needs from entry-level hardware RAID protection (the SA-641 and SA-642 controllers) to maximum performance and flexibility (the SA-6402 and SA controllers); yet, they all share several advanced features that deliver maximum uptime and data reliability. Each Smart Array controller also provides complete data compatibility with previous generations of Smart Array controllers for easy data migration from server to server and for controller upgradeability. 12

13 For more information For additional information, refer to the resources detailed below. Resource description Ultra320 SCSI Maintains SCSI Prevalence technology brief ProLiant Smart Array Controllers web page Smart Array 6400 Controllers web page Smart Array 641/642 and 64MB BBWC Enabler web page Web address pdf html rray6400/index.html rray bbwc/index.html Call to action Please send questions and further comments about this paper to: 2003 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. HP shall not be liable for technical or editorial errors or omissions contained herein. Microsoft and Windows are registered trademarks of Microsoft Corporation. NetWare is a registered trademark of Novell, Inc. UNIX and UnixWare are registered trademarks of The Open Group. Solaris is a registered trademark of Sun Microsystems. O/S2 WARP is a registered trademark of IBM Corporation. The information in this document is subject to change without notice. TC031201TB, 12/2003