Creating Multipath Connections to Dell iscsi Storage Arrays

Transcription

1 Creating Multipath Connections to Dell iscsi Storage Arrays By Dave Jaffe Dell Enterprise Technology Center Jeff Glenn Dell Serviceability Engineering and Richard Hou Dell World Wide Services Dell Enterprise Technology Center delltechcenter.com September 2007

2 Contents Executive Summary... 4 Introduction... 5 The Microsoft iscsi Initiator... 7 Multipath Connection to PowerVault NX1950 iscsi LUNs Using Microsoft MPIO.. 9 PowerPath Multipath Connections to Dell/EMC CX3-20c LUNs using Microsoft MPIO with EMC s PowerPath Multipath Connections to Dell PowerVault MD3000i LUNs using Microsoft MPIO with the Dell MD3000i Device Specific Module for Multi-Path Conclusions Figures Figure 1: Microsoft iscsi Initiator Installation Screen... 8 Figure 2: Network Diagram for MPIO to PowerVault NX Figure 3: PowerVault NX1950 Console... 9 Figure 4: Microsoft iscsi Software Target Properties - Network Adapters Figure 5: Microsoft iscsi Initiator Initial Screen Figure 6: Microsoft iscsi Initiator Discovery Screen Figure 7: Microsoft iscsi Initiator Targets Screen Figure 8: Microsoft iscsi Initiator Log On to Target Screen Figure 9: Microsoft iscsi Initiator Advanced Settings Screen Figure 10: Microsoft iscsi Initiator Targets Screen after Log On Figure 11: Microsoft iscsi Initiator Sessions Screen Figure 12: Microsoft iscsi Initiator Devices Screen Figure 13: Microsoft iscsi Initiator MPIO Screen Figure 14: Disk Management Screen Figure 15: Network Diagram for MS MPIO/PowerPath Connection to CX3-20c Figure 16: Navisphere Manager Screen Showing Front End iscsi Ports Figure 17: Microsoft iscsi Initiator Targets Screen for CX3-20c Figure 18: Microsoft iscsi Initiator Targets Screen for CX3-20c after Log On Figure 19: Microsoft iscsi Initiator Devices Screen for CX3-20c Figure 20: Microsoft iscsi Initiator MPIO Screen for CX3-20c Figure 21: PowerPath Monitor Console September 2007 Page 2 Dell Enterprise Technology Center

3 Figure 22: PowerVault MD3000i Network Diagram Figure 23: Microsoft iscsi Initiator Installation Screen Figure 24: PowerVault MD3000i Installation StorPort Driver Upgrade Required Figure 25: PowerVault MD3000i Installation - Set iscsi Timeout Figure 26: Modular Disk Storage Manager Installation Screen Figure 27: Modular Disk Storage Manager Installation Screen Host Figure 28: Microsoft iscsi Initiator Initial Screen for MD3000i Figure 29: Microsoft iscsi Initiator Discovery Screen for MD3000i Figure 30: Microsoft iscsi Initiator Targets Screen for MD3000i Figure 31: Modular Disk Storage Manager Configure Host Access Screen Figure 32: Modular Disk Storage Manager Configure Host Access - Specify iscsi Initiators Screen Figure 33: Modular Disk Storage Manager Configure Host Access - Specify Host Group Screen30 Figure 34: Modular Disk Storage Manager Host Topology Figure 35: Microsoft iscsi Initiator Log On to Target Screen for MD3000i Figure 36: Microsoft iscsi Initiator Log On Advanced Settings Screen Figure 37: Microsoft iscsi Initiator Target Properties Sessions Screen Figure 38: Microsoft iscsi Initiator Target Properties - Devices Screen Figure 39: Microsoft iscsi Initiator Devices MPIO Screen For Further Information and Discussion Visit our Dell TechCenter wiki at to discuss this paper, and to contribute your experiences in using the Dell PowerVault NX1950 storage for your business. Talk Back Tell us how the Dell Scalable Enterprise Technology Center can help your organization better simplify, utilize, and scale enterprise solutions and platforms. Send your feedback and ideas to Enterprise_Techcenter@dell.com or visit us at dell.com/techcenter. September 2007 Page 3 Dell Enterprise Technology Center

4 Section 1 Executive Summary Multipath I/O, a critical component of highly available iscsi SANs, may be implemented using redundant network subnets and the appropriate software running on the host to manage the paths. This paper includes detailed instructions for connecting a Windows host to the PowerVault NX1950 Windowsbased iscsi target using the Microsoft iscsi Initiator, to Dell/EMC CX3 iscsi arrays using the Microsoft iscsi Initiator in combination with EMC s PowerPath software, and to the Dell PowerVault MD3000i iscsi Storage Array using the Microsoft iscsi Initiator in combination with the Dell MD3000i Device Specific Module for Multi-Path. September 2007 Page 4 Dell Enterprise Technology Center

5 Section 2 Introduction As the requirement for fast, inexpensive, highly available and centrally managed data storage increases, many enterprises are moving from storage attached to individual servers to storage area networks (SANs) accessible to all servers. Traditionally, SANs have been implemented using the Fibre Channel protocol, which requires specialized host bus adapters, switches and cables. In the past few years an alternative shared storage paradigm is emerging that employs iscsi (Internet Small Computer System Interface) to connect the servers to the storage. With iscsi, input/output (I/O) requests are packed into standard Internet protocol (IP) packets and routed to the storage through standard Ethernet cables, switches and routers. By using existing Ethernet infrastructure and expertise, the cost and complexity of using iscsi storage can be significantly less than a Fibre Channel setup. In the past two years Dell has introduced several iscsi platforms. The Dell PowerVault NX1950, which is based on the Microsoft Windows Unified Data Storage Server, provides file sharing using both the Windows Common Internet File System (CIFS) and Unix/Linux/Mac Network File System (NFS) protocols as well as block data through the iscsi protocol. PowerVault NX1950 can be used with either serially attached SCSI (SAS) storage (the PowerVault NX1950 Integrated model) or Fibre Channel storage (the PowerVault NX1950 Gateway). Higher in capability are the Dell/EMC CX3 combination storage arrays, which offer block level access through both iscsi and Fibre Channel connectors: the CX3-10c, CX3-20c and CX3-40c. The newest iscsi offering from Dell is the PowerVault MD3000i iscsi Storage Array, which is a 3-rack unit disk enclosure with the iscsi interface built into RAID controllers installed in the rear of the chassis. The packing of SCSI I/O requests into IP packets on the server may be handled by a dedicated hardware host bus adapter or by a software initiator that communicates with the server s standard network interface card (NIC). For Windows servers, for example, the software Microsoft iscsi Initiator may be used to connect to Dell s iscsi storage arrays. To provide the highest availability and load balancing, redundancy is required throughout the SAN, from server to disks. On the server side, multiple NICs can be used for redundancy. On the iscsi backend arrays, the PowerVault NX1950 Integrated model features redundant SAS connections from its NX1950 controller to its integrated PowerVault MD3000 disk array, while the Dell/EMC CX3 series features redundant storage processors, each of which can access the storage logical units (LUNs).The MD3000i offers redundant RAID controllers each with 2 iscsi ports. To provide full redundancy it is necessary to connect multiple paths from the server to the storage array. For iscsi this requires multiple network subnets, each with its own NIC and Ethernet switches, as well as the software on the server side to load balance the Ethernet packets between the paths and detect when a path is broken and subsequently manage the graceful failover to the alternate path(s). For Microsoft-based iscsi targets such as that in the September 2007 Page 5 Dell Enterprise Technology Center

6 PowerVault NX1950, the Microsoft iscsi Initiator may be configured to manage multipath I/O (MPIO). For the Dell/EMC arrays, the combination of the Microsoft initiator and EMC s PowerPath software provides the most robust MPIO solution. For the PowerVault MD3000i failover software is provided by Dell that integrates with the Microsoft iscsi Initiator to provide the MPIO functionality. This paper shows how each type of connection is created and managed. September 2007 Page 6 Dell Enterprise Technology Center

7 Section 3 The Microsoft iscsi Initiator The Microsoft iscsi Initiator can be used in several different ways to manage connections to the backend iscsi storage target. It can be used as a standalone piece of software communicating to the iscsi target through a regular Gigabit Ethernet network interface card (NIC), an accelerated NIC with TCP/IP Offload Engine hardware, or used to manage a hardware iscsi host bus adapter (HBA). Or it can be used in conjunction with Device Specific Module (DSM) multipathing software typically developed by the array vendor, such as Power Path from EMC (to be discussed in Section 5) or the Dell MD3000i Device Specific Module for Multi-Path. In all cases the Microsoft software iscsi initiator will be treated as a NIC in the server, while hardware initiators will be treated as a storage device in the OS. Although both of them use Microsoft iscsi initiator service, they are treated differently. The tradeoffs between them are cost, server OS overhead, security and manageability. A hardware HBA will be used usually for high performance requirements. In this paper, the discussion will be focus on the pure software initiator. The Microsoft iscsi Software Initiator package is a free download available from microsoft.com. To determine what versions are supported, refer to the target s support matrix (for example, the EMC Support Matrix at and download the latest supported version. Boot from an iscsi LUN using a regular or TOE NIC is only supported with a special boot version of the Microsoft iscsi Software Initiator. The support matrix will usually provide the version information for that purpose. The Microsoft iscsi Software Initiator package contains the following components: msiscsi.sys. This is the mini-port driver used by the regular NIC only. This piece of software moves data from storage stack to standard network stack. iscsiprt.sys. This driver manages Plug and Play, Power Management, Command Queuing, etc. iscsiexe.exe. This manages iscsi initiators for both NICs and HBAs on behalf of the OS. This is also the drive to support isns client and device discovery. Microsoft MPIO Multipathing Support for iscsi (MPIO and iscsi DSM drivers). This is what provides the failover and load balancing to the storage array. During installation of the Microsoft iscsi Initiator, depending on the storage system you are connecting to, MPIO may or may not be selected. For the September 2007 Page 7 Dell Enterprise Technology Center

8 NX1950, select Microsoft MPIO Multipathing Support for iscsi option during the Microsoft iscsi Initiator installation (see Figure 1: Microsoft iscsi Initiator Installation ScreenFigure 1). All iscsi sessions will be managed by MPIO to support multiple paths to the target. The following failover/load balancing policies are available: Failover Only, Round Robin, Round Robin with Subset (round robin among currently active paths), Weighted Path and Least Queue Depth. Figure 1: Microsoft iscsi Initiator Installation Screen A second multipathing policy, multiple connections per session (MCS) is not supported on some arrays and is not discussed here. References and Resources The following link contains various resources and references related to iscsi including whitepapers and support guides mspx Link to download the Microsoft iscsi Software Initiator: The latest version is always maintained at this link. This page will include links to previous versions or patches if applicable. September 2007 Page 8 Dell Enterprise Technology Center

9 Section 4 Multipath Connection to PowerVault NX1950 iscsi LUNs Using Microsoft MPIO This section documents creating multipath connections to PowerVault NX1950 iscsi LUNs using the multipath IO (MPIO) feature of the Microsoft software iscsi initiator. A PowerEdge 2950 server running 64-bit Windows Server 2003 R2, r3win2950b, was connected to a PowerVault NX1950 using network subnets and (see Figure 2). In this configuration the other two NICs on the PowerVault NX1950 can be teamed for Networked Attached Storage access. Figure 2: Network Diagram for MPIO to PowerVault NX1950 Using the PowerVault NX1950 Console, the iscsi target R1NXISCSI was added with Virtual Disk 0 created on a 5-disk RAID 5 LUN on the PowerVault NX1950's integrated MD3000 (see Figure 3). Figure 3: PowerVault NX1950 Console September 2007 Page 9 Dell Enterprise Technology Center

10 It is recommended to restrict the networks available to iscsi discovery to just those that have iscsi targets attached; otherwise all networks associated with the PowerVault NX1950 will be visible to the iscsi initiator. To do this, right click on Microsoft iscsi Software Target (R1NXISCSI) and select the appropriate networks, as shown in Figure 4. Figure 4: Microsoft iscsi Software Target Properties - Network Adapters September 2007 Page 10 Dell Enterprise Technology Center

11 On the r3win2950b the Microsoft iscsi Initiator 2.04 was installed from Initiator build3273-amd64fre.exe and started as shown in Figure 5. Figure 5: Microsoft iscsi Initiator Initial Screen Next, the r3win2950b s Initiator Node Name (also known as the iscsi Qualified Name or IQN), iqn com.microsoft:r3win2950b.setc.com, was added to the R1NXISCSI target using the PowerVault NX1950 console. On the MS iscsi Initiator Discovery tab the two IP addresses of the PowerVault NX1950 ( and ) were added as shown in Figure 6. Figure 6: Microsoft iscsi Initiator Discovery Screen September 2007 Page 11 Dell Enterprise Technology Center

12 After the PowerVault NX1950 s iscsi target address was entered into the Discovery screen its iscsi LUN showed up in the Targets tab. The LUN was selected and then Log On was selected as shown in Figure 7. Figure 7: Microsoft iscsi Initiator Targets Screen Note: an alternate approach to entering the IQN into the iscsi target is to enter the IP address of the target in the Discovery screen first, then Browse for iscsi initiators in the iscsi target using the PowerVault NX1950 Console. The IQN of the server should be listed. On the Log On to Target screen "Automatically restore this connection when the system boots" and "Enable multi-path" were selected, then the Advanced features were selected: Figure 8: Microsoft iscsi Initiator Log On to Target Screen On the Advanced Setting screen as shown in Figure 9 the following selections were made: Local Adapter: Microsoft iscsi Initiator, Source IP: , Target Portal: (CHAP logon and IPSec, which provide authentication and encryption, were not used in this test). September 2007 Page 12 Dell Enterprise Technology Center

13 Figure 9: Microsoft iscsi Initiator Advanced Settings Screen After selecting OK twice the LUN showed as Connected: Figure 10: Microsoft iscsi Initiator Targets Screen after Log On September 2007 Page 13 Dell Enterprise Technology Center

14 The Log On was repeated, this time with a Source IP ( ) and Target Portal ( /3260) from the second subnet, after which Details on the Target tab showed two sessions are connected to the LUN: Figure 11: Microsoft iscsi Initiator Sessions Screen Note: multiple connections per section are not supported with the PowerVault NX 1950 or the Dell/EMC CX3 iscsi storage arrays. On the Target Properties Devices tab two devices appeared, one for each path: Figure 12: Microsoft iscsi Initiator Devices Screen September 2007 Page 14 Dell Enterprise Technology Center

15 The Advanced feature of the first device was selected. On the MPIO tab, Fail Over Only, Round Robin and other load balance policies were available. With Fail Over Only one path is active and one is standby (shown in Figure 13). In Round Robin both paths are active. Note that MPIO policies are per device so they can be set differently on different LUNs. Figure 13: Microsoft iscsi Initiator MPIO Screen The LUN was now present in Disk Management where it was initialized, assigned a disk letter and had partitions created on it: Figure 14: Disk Management Screen Complete details and screen shots are available at the Dell TechCenter wiki at September 2007 Page 15 Dell Enterprise Technology Center

16 Section 5 PowerPath Just as in a Fibre Channel-based SAN environment, a well designed iscsi SAN should have more than one path from the host to the target LUN through adapter, cable, switch, etc to balance the IO load, as well as to facilitate recovery in case of failure. The challenge is with each path available to the server, the LUN will be presented many times on the server side. This will require a host based software to manage the multipathing environment. PowerPath is the EMC host based multipathing management software that is responsible for failover and load balancing. PowerPath will monitor all the paths to the target LUN, and optimizes multipath LUNs with load-balancing algorithms. PowerPath offers several load-balancing algorithms that are based on access patterns. It removes any failed paths from the configuration, and reroutes data to the remaining live paths. If all the paths are up, PowerPath will balance the I/O load across the paths based on the method specified on the PowerPath management console, and determine which path will yield the fastest response time for the I/O request. If one of the path fails, PowerPath handles the failover of a LUN from one path to others, depends on which device failed. For example, if the Storage Processor (SP) failed, PowerPath will trespass the LUN to another SP. This is transparent to the host so it will not interrupt the server IO. EMC has different versions of PowerPath to support iscsi environment. One is the regular PowerPath that can be used for both FC and iscsi environment, the other one is the specific PowerPath iscsi. PowerPath iscsi is EMC s specific path management software for Windows bit environment that is developed based on Microsoft MPIO framework There are two license of PowerPath iscsi: Base License. This will provide both frontend and backend failover and supports a maximum of 8 paths to a LUN. Unlicensed. This is also called PowerPath iscsi SE or the Utility Kit, which provides only backend failover and max 2 paths to a LUN. Neither mode supports load balancing. Starting with version 4.6, the regular PowerPath was developed to utilize the Microsoft Initiator Device Specific Module code and thus is fully supported by Microsoft. For this reason the PowerPath 4.6 is recommended over PowerPath iscsi. Dell/EMC bundled the PowerPath license in the AX product family and the CX3-10c. For these arrays, the maximum number of servers supported is covered by the PowerPath license. For other kind of arrays, if the server is using only one NIC for iscsi, customers can use the PowerPath SE, which is the free version September 2007 Page 16 Dell Enterprise Technology Center

17 that will support backend failover only. Servers using more than one NIC for iscsi need to have a purchased license of PowerPath. When installing the Microsoft iscsi Initiator on Dell/EMC storage systems, selection of the Microsoft MPIO Multipathing Support for iscsi option (see Figure 1) depends on which version of PowerPath is used: PowerPath 4.6 or later select the MPIO option PowerPath 4.5 do not select the MPIO option PowerPath iscsi 1.1 select the MPIO option September 2007 Page 17 Dell Enterprise Technology Center

18 Section 6 Multipath Connections to Dell/EMC CX3-20c LUNs using Microsoft MPIO with EMC s PowerPath This section documents creating multipath connections to iscsi LUNs on a Dell/EMC CX3-20c using the Multipath IO feature of the Microsoft software iscsi Initiator plus EMC s PowerPath for load balancing and failover. The server connecting to the CX3-20c iscsi LUN was server r3win2950a running 64-bit Windows Server 2003 R2. As shown in Figure 15 and Figure 16, each CX3-20c storage processor (SP) had four iscsi front end ports of which two were used in this demo, with one each in the and subnets. The r3win2950a connected to both network subnets. Figure 15: Network Diagram for MS MPIO/PowerPath Connection to CX3-20c The EMC Navisphere Server Utility was used to register the r3win2950a host iscsi initiator s iscsi Qualified Name (IQN) with the a0, a1, b0 and b1 ports of CX3-20c array. (This can also be done manually using Connectivity Status from the top level of Navisphere). Then LUNs were created and placed in the same storage group as the r3win2950a host (with two LUNs owned by SP A and two owned by SP B). On the r3win2950a the Microsoft iscsi Initiator 2.04 was installed from Initiator build3273-amd64fre.exe and EMC s PowerPath was installed from EMCPP.W2003_x GA.exe. The MS iscsi Initiator was started (see Figure 5) and on the Discovery tab the IP addresses of the 4 CX3-20c iscsi ports were added (similar to Figure 6) September 2007 Page 18 Dell Enterprise Technology Center

19 Figure 16: Navisphere Manager Screen Showing Front End iscsi Ports All 8 iscsi front end ports showed up in the Targets tab. Note the port address (a0, a1, etc., at the end of each target IQN): Figure 17: Microsoft iscsi Initiator Targets Screen for CX3-20c September 2007 Page 19 Dell Enterprise Technology Center

20 Using the Log On function a connection was made to the connected ports (a0, a1, b0 and b1) as shown in Figure 18. Figure 18: Microsoft iscsi Initiator Targets Screen for CX3-20c after Log On With the first target selected, the Details screen was brought up. All four LUNs appeared on the Devices tab: Figure 19: Microsoft iscsi Initiator Devices Screen for CX3-20c September 2007 Page 20 Dell Enterprise Technology Center

21 The Advanced features of the four devices were selected in turn. On the MPIO tab for each LUN Vendor Specific was showing, which indicates that PowerPath will be used for failover/load balancing: Figure 20: Microsoft iscsi Initiator MPIO Screen for CX3-20c The PowerPath Monitor (Figure 21) showed four paths to each LUN, one for each port. Although all four paths were shown as Active, only the two connecting to ports on the storage processor to which the LUN is currently owned will be in use at any given time. If the paths to both ports of that storage processor are disabled, the CX3-20c will trespass the LUN to the other storage processor. The LUNs were now present in Disk Management where they were initialized, assigned a disk letter and had partitions created on them. Note that connections must be made to four ports on the CX3 array for complete multipathing. This leaves four additional iscsi front end ports that may also be connected and assigned to a separate server for load balancing. Complete details and screen shots are available at the Dell TechCenter wiki at September 2007 Page 21 Dell Enterprise Technology Center

22 Figure 21: PowerPath Monitor Console September 2007 Page 22 Dell Enterprise Technology Center

23 Section 7 Multipath Connections to Dell PowerVault MD3000i LUNs using Microsoft MPIO with the Dell MD3000i Device Specific Module for Multi-Path This section documents creating multipath connections to iscsi LUNs on a Dell PowerVault MD3000i using the Microsoft iscsi Initiator plus Dell s MD3000i iscsi software. The server connecting to the MD3000i iscsi LUN was server r3win2950b running 64-bit Windows Server 2003 R2. As shown in Figure 22, each MD3000i controller had two iscsi ports, with one each in the and subnets. The r3win2950b connected to both network subnets. Figure 22: PowerVault MD3000i Network Diagram The MD3000i uses its own Device Specific Module code and thus required special installation of the Microsoft iscsi Initiator. Therefore, on the server being connected to MD3000i (r3win2950b in this case), the existing Microsoft iscsi Initiator instance was uninstalled and the server was rebooted. Then the Microsoft initiator was installed from Initiator-2.04-build3273-amd64fre.exe. All installation options except Microsoft MPIO Multipathing Support for iscsi were selected: September 2007 Page 23 Dell Enterprise Technology Center

24 Figure 23: Microsoft iscsi Initiator Installation Screen To install the Dell MD3000i iscsi software, it was necessary to insert the PowerVault MD3000i Resource CD. Upon starting, the software showed a message that it was necessary to upgrade the StorPort driver. The hot fix was unzipped to the local hard drive by clicking on the error message and then run. Figure 24: PowerVault MD3000i Installation StorPort Driver Upgrade Required After rebooting the Resource CD was inserted again, Install MD3000i Storage Software was selected and the iscsi timeout value was adjusted by selecting OK at the next prompt: September 2007 Page 24 Dell Enterprise Technology Center

25 Figure 25: PowerVault MD3000i Installation - Set iscsi Timeout Following this the PowerVault Modular Disk Storage Manger (MDSM) installation screen appeared: Figure 26: Modular Disk Storage Manager Installation Screen After selecting the language the Select Installation Type screen came up: September 2007 Page 25 Dell Enterprise Technology Center

26 Figure 27: Modular Disk Storage Manager Installation Screen Host Host was selected since the MD3000i was already being managed from another server. Upon completion of the installation the Microsoft iscsi Initiator was started: Figure 28: Microsoft iscsi Initiator Initial Screen for MD3000i September 2007 Page 26 Dell Enterprise Technology Center

27 In the Discovery tab, the four IP addresses of the MD3000i were entered: Figure 29: Microsoft iscsi Initiator Discovery Screen for MD3000i No LUNs were discovered since the host had not been given access to the MD3000i. The Targets tab at this point looked like: Figure 30: Microsoft iscsi Initiator Targets Screen for MD3000i September 2007 Page 27 Dell Enterprise Technology Center

28 The MDSM Configure Host Access (Manual) function was used to give the host access to the MD3000i. First, the host name and operating system type were entered: Figure 31: Modular Disk Storage Manager Configure Host Access Screen Then the host s iscsi initiator was added to the list of Selected iscsi Initiators: September 2007 Page 28 Dell Enterprise Technology Center

29 Figure 32: Modular Disk Storage Manager Configure Host Access - Specify iscsi Initiators Screen On the next screen it was specified that this host will not share virtual disks with other hosts: September 2007 Page 29 Dell Enterprise Technology Center

30 Figure 33: Modular Disk Storage Manager Configure Host Access - Specify Host Group Screen Upon creation a Virtual Disk was created on the MD3000i and mapped to the host. The final Host Topology is shown in Figure 34. September 2007 Page 30 Dell Enterprise Technology Center

31 Figure 34: Modular Disk Storage Manager Host Topology Back on the Microsoft initiator on the host, the MD3000i Target was selected and Log On selected: Figure 35: Microsoft iscsi Initiator Log On to Target Screen for MD3000i On the Advanced Settings screen, a Source IP and Target Portal in the same subnet were selected using the dropdown menus: September 2007 Page 31 Dell Enterprise Technology Center

32 Figure 36: Microsoft iscsi Initiator Log On Advanced Settings Screen The logon was repeated with the other three combinations of Source and Target IPs ( , , ). The four sessions were seen in the MD3000i target s details: Figure 37: Microsoft iscsi Initiator Target Properties Sessions Screen September 2007 Page 32 Dell Enterprise Technology Center

33 The four connections to the LUN (Dell MD3000 SCSI Disk Device) were visible in the Devices tab of any of the sessions: Figure 38: Microsoft iscsi Initiator Target Properties - Devices Screen The load balance policy may be set by selecting Advanced. Round Robin with Subset is the default. Note that the two paths corresponding to the MD3000i controller that currently owns the LUN are Active; the other two are in Standby mode: Figure 39: Microsoft iscsi Initiator Devices MPIO Screen September 2007 Page 33 Dell Enterprise Technology Center

34 Section 8 Conclusions To maximize the performance and availability of Dell s iscsi storage arrays it is necessary to create multiple network connections from the host to the array and manage them with software to handle the load balancing and failover. As shown in detail in this paper, the Microsoft iscsi Initiator, either by itself (for Windowsbased iscsi targets such as that on the Dell PowerVault NX1950) or in conjunction with EMC s PowerPath software (for the Dell/EMC CX3 iscsi arrays), or with the Dell MD3000i Device Specific Module for Multi-Path, can be readily deployed to achieve this. THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND. Dell, PowerEdge and PowerVault are trademarks of Dell Inc. Exchange and SQL Server are registered trademarks of Microsoft Inc. Intel and Xeon are registered trademark of Intel Corp. Red Hat is a registered trademark of Red Hat Inc. Linux is a registered trademark of Linus Torvalds. Other trademarks and trade names may be used in this document to refer to either the entities claiming the marks and names or their products. Dell disclaims proprietary interest in the marks and names of others Pricing, specifications, availability, and terms of offers may change without notice. Taxes, fees, shipping, handling and any applicable restocking charges are extra, and vary. Copyright 2007 Dell Inc. All rights reserved. Reproduction in any manner whatsoever without the express written permission of Dell Inc. is strictly forbidden. For more information, contact Dell. Information in this document is subject to change without notice. September 2007 Page 34 Dell Enterprise Technology Center