Transcript
iSCSI technologies in HP ProLiant servers using advanced network adapters technology brief 2nd Edition
Abstract.............................................................................................................................................. 2 Introduction......................................................................................................................................... 2 iSCSI message exchange...................................................................................................................... 2 iSCSI functionality................................................................................................................................ 4 Operating distance .......................................................................................................................... 4 Security........................................................................................................................................... 4 FlexFabric Adapters with full iSCSI offload.............................................................................................. 5 Multifunction network adapters with accelerated iSCSI............................................................................. 6 iSCSI boot .......................................................................................................................................... 7 iSCSI boot for FlexFabric adapters ..................................................................................................... 7 Configuring iSCSI boot using Virtual Connect Manager........................................................................ 7 iSCSI boot on multifunction network adapters ...................................................................................... 9 iSCSI and HP Storage products ............................................................................................................. 9 iSCSI SANs ..................................................................................................................................... 9 iSCSI interoperability with Fibre Channel SANs................................................................................... 9 Conclusion........................................................................................................................................ 10 For more information.......................................................................................................................... 11 Call to action .................................................................................................................................... 11
Abstract This technology brief explains iSCSI technologies you will find in HP ProLiant servers. It also explains how these simple and cost-effective technologies benefit your data center. It covers the accelerated iSCSI implementation for embedded and optional multifunction NICs. It also describes the full offload iSCSI functionality available on HP FlexFabric adapters. These adapters are integrated onto some G7 HP BladeSystem servers and are available as mezzanine cards for G6 BladeSystem servers.
Introduction iSCSI is a standard that implements the SCSI protocol for interacting with storage devices over a TCP/IP network, typically over Gigabit Ethernet. Like Fibre Channel (FC), iSCSI lets servers access shared storage devices over a network. Unlike FC-SAN, iSCSI does not require a separate, special purpose network. This reduces the cost and complexity of having shared network storage. As part of the iSCSI working group of the Internet Engineering Task Force (IETF), HP engineers had hands-on involvement in writing the iSCSI specification. HP also developed the first multifunction network adapter that combined Ethernet and iSCSI capabilities in a single network card, including support for TCP/IP offload engine (TOE) and iSCSI acceleration.
iSCSI message exchange iSCSI follows the SCSI architectural model which is based on message exchange between an initiator and a storage resource, or target (Figure 1).
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Figure 1. Diagram of block storage using SCSI (left) and iSCSI (right)
iSCSI initiators access targets using the iSCSI protocol. While the target is usually a hard drive enclosure or another computer, it can also be any other storage device that supports the iSCSI protocol, such as a tape drive. The iSCSI stack at both ends of the path puts SCSI block commands into Ethernet packets for transmission over IP networks. Figure 2 illustrates a message exchange between an initiator and a target. The process begins when an application sends a request to the operating system (OS) to read or write data. The OS generates the appropriate SCSI commands and data request in the form of a message. Before the message can be sent over an IP network, it is processed through iSCSI to place the request into the TCP/IP protocol stack (attaching routing, error checking, and control information) for transmission over the network. This process uses driver- or OS-level software, or it can be offloaded to the host bus adapter (HBA). The HBA transmits the packets over the IP network. When the packets reach the target device, they go through a reverse process to reassemble the data which is then moved to the SCSI controller. The SCSI controller fulfills the request by writing data to or reading data from the target device. If it is a read transaction, the target returns data to the initiator using the iSCSI protocol.
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Figure 2. Message exchange between an initiator and target using the iSCSI protocol mode
Initiators include software initiators and hardware initiators (accelerated or offload HBAs). Software initiators require CPU resources to manage the protocol stack. A more efficient approach is to offload the protocol management to an iSCSI HBA, such as the HP NC551i Dual Port FlexFabric 10 Gb Network Adapter
iSCSI functionality iSCSI provides ProLiant servers ready access to storage resources using the same protocols that are used for networking. Upgrading from direct attached storage (DAS) to iSCSI-connected storage gives you greater flexibility and asset utilization. Using common infrastructure reduces complexity and cost. Consolidating storage in a centralized pool using network attached storage leads to greater efficiency because servers can have shared access to storage. You can also manage, resize, and protect the network attached storage pool from a single control point.
Operating distance It is possible for an iSCSI-based network to economically span great distances using commonly available wide area networks (WANs). Longer operating distances lets you mirror and archive data at remote sites to meet disaster protection and business continuity goals.
Security IP networks have a well-defined security infrastructure (encryption and authentication) that makes iSCSI viable for remote back up and disaster recovery applications. FC networks, on the other hand, are primarily protected with physical security. Encryption An iSCSI transfer can optionally encrypt each packet, ensuring security until the packet is decrypted by the receiver. A set of protocols developed by the IETF called Internet Protocol Security (IPSEC)
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describes two encryption modes: transport and tunnel. Transport mode encrypts only the data portion (payload) of each packet and leaves the header untouched. Tunnel mode, on the other hand, encrypts both the header and the payload for increased security. Authentication iSCSI has provisions for servers and storage devices to prove their identities to each other. It uses the Challenge Handshake Authentication Protocol with Diffie-Hellman key protocol (DH CHAP). IPSEC can provide further protection with per-packet authentication.
FlexFabric Adapters with full iSCSI offload. The FlexFabric Adapters give you up to four Flex-10 physical function connections with adjustable bandwidth control. FlexFabric also provides either offloaded iSCSI or offloaded Fiber Channel over Ethernet (FCoE) functionality for one of the four connections. The iSCSI functionality is fully offloaded and represents an advance over the accelerated iSCSI available on multifunction network adapters. Accelerated iSCSI with full offload executes the entire iSCSI stack on the FlexFabric adapter instead of the host server. This lets the FlexFabric adapter present a PCI storage function to the host operating system, eliminating the need for virtual bus driver software (Figure 3). Additional iSCSI functionality, including iSCSI boot management, is also performed on the adapter. This new architecture delivers several advantages: Simplifies device driver design, improving reliability and stability Provides the lowest host CPU utilization and highest iSCSI performance Allows iSCSI boot configuration for a group of HP BladeSystem servers to be managed over the network without running separate utilities on each host server
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Figure 3. Software stack for full offload iSCSI on the FlexFabric adapter.
Multifunction network adapters with accelerated iSCSI Until recently, the typical server environment required separate connectivity products for networking, storage, interconnects, and infrastructure management. HP multifunction network adapters function as both iSCSI HBAs and Ethernet NICs, so they support multiple functions through a single connection. Ethernet server adapters with accelerated iSCSI simplify network infrastructure by functioning as network adapters and as storage HBAs, providing access to storage boxes and servers over a single connection. HP multifunction adapters support hardware-assisted accelerated iSCSI operation― the offloading of parts of the iSCSI software to the server adapter for improved system performance. Accelerated iSCSI uses a TCP/IP Offload Engine (TOE) to execute parts of the iSCSI stack on the adapter rather than on the server host OS. The TOE translates SCSI block commands into NIC packets and manages their transmission and receipt. These functions include all of the following: Segments SCSI blocks into TCP/IP packets (including header replication) when sending SCSI blocks to a target device De-segments packets back to iSCSI blocks when receiving data from a target device Manages acknowledgements and retransmissions Accelerated iSCSI does not offload processing of iSCSI protocol. It is executed in the OS on the server side. The multifunction network adapter still presents a PCI NIC function to the system, requiring a virtual bus driver on the server to make the NIC look like a SCSI initiator to the operating system.
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You must use HP ProLiant Essentials Accelerated iSCSI Pack to enable accelerated iSCSI on HP servers with embedded Multifunction Gigabit Ethernet server adapters. It is not required for the multifunction mezzanine cards and multifunction Gigabit Ethernet server adapters because accelerated iSCSI is included on these optional cards. For more information on the Accelerated iSCSI Pack, please go to www.hp.com/go/iscsi. A complete list of ProLiant networking adapters and mezzanine cards for ProLiant BladeSystem servers is available at http://h18004.www1.hp.com/products/servers/networking/index-nic.html.
iSCSI boot iSCSI boot lets the host server boot from a remote OS image located on a SAN. An iSCSI firmware image (iSCSI boot option ROM) on the host server makes the remote disk drive appear as a local, bootable C: drive. The server is configured to connect to and boot from the iSCSI target disk on the network and to download the OS image from the iSCSI target disk.
iSCSI boot for FlexFabric adapters HP FlexFabric adapters feature iSCSI boot support as part of the base product. In addition to providing iSCSI boot support for Red Hat, SUSE Linux®, or Microsoft® Windows® Server environments, FlexFabric adapters will also support iSCSI boot in various Virtual Machine environments, including VMware ESXi 4.1. iSCSI boot for FlexFabric is not supported on earlier versions of VMware.
Configuring iSCSI boot using Virtual Connect Manager The HP FlexFabric adapter supports configuration of iSCSI boot parameters using the HP Virtual Connect Manager 3.10 for the HP BladeSystem enclosure. This eliminates the need to use traditional remote connection tools to access each server individually and configure iSCSI boot using server-side software utilities. From the Virtual Connect console, you can manage the iSCSI boot configurations for iSCSI initiator functions on multiple servers’ FlexFabric adapters (Figure 4).
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Figure 4. FlexFabric iSCSI Connections shown in Virtual Connect
Configuring iSCSI Boot parameters in Virtual Connect
As Figure 4 shows, the FlexFabric adapter lets you configure both a primary and secondary iSCSI boot path for the iSCSI function.
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The iSCSI function on the FlexFabric adapter can support up to 128 separate iSCSI targets. Unlike iSCSI boot parameters, additional iSCSI targets are configured through the iSCSI BIOS utility that is part of the FlexFabric adapter option ROM. You can access the iSCSI BIOS utility using the CTRL-S key sequence during server POST.
iSCSI boot on multifunction network adapters Within a Red Hat, SUSE Linux®, or Microsoft® Windows® Server environment, the HP iSCSI boot solution for multifunction network adapters includes scripts to significantly simplify installation. HP supplies the iSCSI boot option ROM at no cost to users. Adding an iSCSI HBA card is not required. The HP NC-Series iSCSI Boot Package for Windows is available here: http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&s wItem=MTX-028ce39726d74abfbb046f153f&jumpid=reg_R1002_USEN). The HP NC-Series iSCSI Boot Direct Install Package for Linux is available here: http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=US&s wItem=MTX-212a7a437b374218b9fe4e8db0. Various HP multifunction network adapters support iSCSI boot capability. For more information on ProLiant network adapters and their capabilities, please visit http://h18004.www1.hp.com/products/servers/networking/index-nic.html.
iSCSI and HP Storage products Using the iSCSI protocol, HP ProLiant servers can connect to any valid iSCSI target in the IP network and map to a logical drive. The iSCSI initiator on the ProLiant server sees a logical SCSI block device, regardless of whether the volume on the target is a physical disk, an array, or a SAN volume. Several HP StorageWorks product families incorporate iSCSI target support as one of the primary means for servers to access their storage resources. These include the HP StorageWorks X1000 series Network Storage Systems, 2000 series Modular Smart Arrays and P4000 series SANs. Each of these product families provides different levels of storage capability. You can find detailed information about HP StorageWorks iSCSI Solutions at http://www.hp.com/go/iscsi.
iSCSI SANs iSCSI allows servers to access storage resources across a TCP/IP Ethernet network. Even though iSCSI traffic can run over the primary LAN network, it significantly increases network traffic. Under these circumstances, an iSCSI implementation cannot provide consistent low latency storage throughput. The best option is to run storage traffic over a separate physical Ethernet network, or over a separate virtual LAN (VLAN). This creates an iSCSI SAN, which is architecturally similar to how Fibre Channel SANs are implemented.
iSCSI interoperability with Fibre Channel SANs Fibre Channel SANs are still the ultimate in performance, reliability, and storage capabilities. They store mission critical data that must be preserved at all costs. They use attached storage systems with redundancy at every level and advanced capabilities such as storage clustering, snapshot capability, and advanced storage volume management. Servers have traditionally used Fibre Channel HBAs to access this storage across the dedicated Fibre Channel network. The HP X3000 series Network Storage Gateway lets HP ProLiant servers access storage volumes on the Fibre Channel SAN using the iSCSI protocol. The X3000 acts as mediator, accepting iSCSI
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protocol from the initiators on the Ethernet TCP/IP network and translating it to FC protocol for the storage volumes on the FC SAN (Figure 5). Servers that are not directly tied to the FC SAN have access to its storage resources if needed.
Figure 5. HP X3000 series Network Storage Gateway as an iSCSI gateway to Fibre Channel SAN storage
Conclusion iSCSI technologies implemented in the HP FlexFabric and HP multifunction network adapters provide a simple infrastructure option for ProLiant servers to access shared storage in data center environments. Hardware-based iSCSI initiators accelerate the connection between host servers and storage to significantly increase performance. Using iSCSI instead of Fibre Channel can potentially result in a lower total cost of ownership (TCO).
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For more information For additional information, refer to the resources listed below. Resource description
Web address
HP iSCSI SAN Solutions Homepage
http://www.hp.com/go/iscsi
HP Virtual Connect
http://www.hp.com/go/virtualconnect
Server-to-network edge technologies: converged networks and virtual I/O
http://h20000.www2.hp.com/bc/docs/support/SupportManu al/c02044591/c02044591.pdf
HP ProLiant networking Ethernet network adapters
http://h18004.www1.hp.com/products/servers/networking/in dex-nic.html
HP ProLiant iSCSI Boot for Linux User Guide
http://h10032.www1.hp.com/ctg/Manual/c02069527.pdf
Tolly Group’s test summary of HP Accelerated iSCSI solution
http://www.tolly.com/TS/2008/HewlettPackard/iSCSISolutions /Tolly208305HPiSCSI.pdf
Configuring iSCSI in a VMware ESX Server 3 Environment
http://www.vmware.com/pdf/vi3_iscsi_cfg.pdf
HP Simply Storage Consolidation guide
http://h20195.www2.hp.com/v2/GetPDF.aspx/4AA22919ENW.pdf
Call to action Send comments about this paper to
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© 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. HP shall not be liable for technical or editorial errors or omissions contained herein. SUSE is a registered trademark of Novell, Inc. Microsoft, Windows are registered trademarks of Microsoft Corporation. VMware is a registered trademark of VMware, Inc. TC100708TB, August 2010
