EMC Performance Protocol Testing Enabled by EMC Celerra, and the

Transcription

1 EMC Performance Protocol Testing Enabled by EMC Celerra, and the iscsi and NFS Protocols Applied Technology Abstract As the use of virtualized data centers in the private cloud continues to expand, the physical connections between servers and SAN storage resources become more critical. Our testing shows that using link aggregation in storage subnets for NFS and iscsi datastores helps data center managers reduce costs, increase efficiency, and safeguard the availability of resources and applications. November 2009

2 Copyright 2009 EMC Corporation. All rights reserved. EMC believes the information in this publication is accurate as of its publication date. The information is subject to change without notice. THE INFORMATION IN THIS PUBLICATION IS PROVIDED AS IS. EMC CORPORATION MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WITH RESPECT TO THE INFORMATION IN THIS PUBLICATION, AND SPECIFICALLY DISCLAIMS IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Use, copying, and distribution of any EMC software described in this publication requires an applicable software license. For the most up-to-date listing of EMC product names, see EMC Corporation Trademarks on EMC.com All other trademarks used herein are the property of their respective owners. Part number: H6724 Applied Technology 2

3 Table of Contents Executive summary... 4 Introduction... 5 Multipath performance analysis... 6 Key components... 7 Physical architecture... 8 Environment profile... 9 Test design and validation NFS datastore link aggregation NFS datastore no link aggregation NFS performance results NFS datastore troubleshooting iscsi datastore link aggregation iscsi datastore No link aggregation iscsi performance results iscsi datastore troubleshooting Performance analysis Conclusion Applied Technology 3

4 Executive summary Business case Data center managers are looking to virtualization as a means to reduce costs, increase efficiency, and deliver the service levels they require. In a virtualized data center, physical server consolidation results in reclaiming valuable data center space, realizing higher use rates, increasing operational efficiencies, and improving availability of resources and applications. As virtualized data centers expand, the physical connections between the servers and SAN storage resources become more critical. Product solution EMC Celerra can meet an organization s data storage needs with a wide range of supported storage protocols including: NAS (including NFS and CIS) iscsi Fibre Channel NFS and iscsi become the protocols of choice when using Ethernet resources. Key results Our testing showed the effects of using link aggregation in single and multiple storage subnets for NFS and iscsi datastores. Applied Technology 4

5 Introduction Purpose This Applied Technology white paper can assist you in planning a vsphere environment on EMC Celerra technology to take advantage of the high-availability features of NFS or iscsi datastores. These environments include: Link aggregation Single storage subnet Two storage subnets Without link aggregation Single storage subnet Two storage subnets Audience This white paper is intended for EMC employees, partners, and customers including IT planners, virtualization architects and administrators, and any other IT professionals involved in evaluating, acquiring, managing, operating, or designing a private cloud environment leveraging EMC technologies. Applied Technology 5

6 Multipath performance analysis Introduction To ensure maximum resource availability, a data center infrastructure must Provide multiple physical data paths between the server and the storage resources Allow path rerouting around problems such as failed components Balance the traffic loads across multiple physical paths Multipathing To maintain a constant connection between a virtualized server host and its storage, a technique called multipathing is used. Multipathing maintains more than one physical path for data between the host and the storage device. If any element in the SAN fails such as an adapter, switch, or cable, the virtualized server host can switch to another physical path that does not use the failed component. The process of path switching to avoid failed components is known as path failover. Load balancing In addition to path failover, multipathing provides load balancing. Load balancing is the process of distributing loads across multiple physical paths to reduce or remove potential I/O traffic bottlenecks. Applied Technology 6

7 Key components Introduction For the high-availability scenario described in this white paper, NFS and iscsi datastores are deployed in a virtualized data center that includes: Three VMware vsphere ESX 4 servers (user hosts) Cisco Catalyst 3750-E Ethernet switches EMC Celerra NS-120 I/O simulation software Cisco Catalyst 3750E Cisco Catalyst 3750 is an energy-efficient, Layer 3, faster Gigabit Ethernet, stackable switch. Cisco Catalyst switches uses StackWise technology that unites up to nine individual switches into a single logical unit using special stack interconnect cables and stacking software. EMC Celerra NS-120 EMC Celerra NS-120 is an affordable unified storage system that scales to 120 drives. With Celerra NS-120, you can connect to multiple storage networks via network-attached storage (NAS), iscsi, Fibre Channel SAN, and Celerra Multi-Path File System (MPFS). vsphere 4 VMware vsphere 4 is the next logical step in IT computing, allowing customers to bring the power of cloud computing to their IT infrastructures. Building on the power of VMware Infrastructure, VMware vsphere 4 increases control over IT environments by supporting many OS, application, and hardware products. VMware vsphere 4 is built on a proven virtualization platform to provide the foundation for internal and external clouds, using federation and standards to bridge cloud infrastructures creating a secure, private cloud. Organizations of all sizes can achieve the full benefits of cloud computing, delivering the highest levels of application service agreements with the lowest total cost per application workload. This data center solution delivers flexible, automatic I/O load balancing, powerful processing power, and simplified network switch management with these features introduced in VMware vsphere 4: EMC PowerPath /VE path failover integration (via VMware vstorage API for Multipathing) As demonstrated in this solution, PowerPath/VE constantly adjusts I/O path usage and responds to changes in I/O loads from VMs. 8 vcpu support Increases the maximum number of virtual CPUs that can be assigned to a guest VM from four to eight. VMware vnetwork Distributed Switch Takes the vswitch capability one step further by extending the connections across the entire cluster. I/O simulation software The following load simulation software is used: IOMeter Applied Technology 7

8 Physical architecture Architecture diagram The following illustration depicts the overall physical architecture of the test environment. Two NICs on each server are used for either NFS or iscsi connection based on the test case. The virtual machines are running IOMeter Dynamo with IOMeter master running on the vcenter server. Each IOMeter Dynamo VM has one data disk hosted on its own iscsi or NFS datastore. The OS disks are hosted on a shared datastore. Applied Technology 8

9 Environment profile Hardware resources The hardware used in the performance analysis environment is listed in the following table. Equipment Quantity Configuration EMC Celerra NS-120 running DART Nine file systems One 510 GB file system containing: 1 x 498 GB iscsi LUN Eight 537 GB file systems containing: 1 x 268 GB iscsi LUN per file system 1 x NFS export per file system Dell x Intel Xeon 4 Core (54xx) 32 GB RAM Ethernet switch 2 Cisco Catalyst 3750-E 2 x Intel 82575GB Quad Gigabit Ethernet NIC Virtual allocation of hardware resources Virtual Machine vcenter DC VM1 to VM8 The following table shows the virtual machine allocation. Resource 2 vcpus 4 GB RAM 20 GB HDD (LSI Logic SCSI Controller) 1 virtual NIC 2 vcpus 4 GB RAM 20 GB HDD (LSI Logic SCSI Controller) 1 virtual NIC 1 vcpu 1 GB RAM 20 GB HDD (LSI Logic SCSI Controller) 100 GB HDD (Paravirtualized SCSI Controller) 1 virtual NIC Applied Technology 9

10 Software resources The software that we used in the performance analysis environment is listed below. Software Version vsphere Enterprise Plus 4.0 (build ) vcenter 4.0 GA (build B162856) PowerPath/VE 5.4 (build 257) IOMeter Dynamo Applied Technology 10

11 Test design and validation Introduction This section outlines the test plan and implementation for the test environment used for this white paper. Test plan Create and deploy eight virtual machines running Windows 2003 Four VMs on one server Four VMs on a second server Use a Paravirtual SCSI driver to access the data disks Create a 100 GB data disk on a iscsi or NFS datastore based on the test case The data disk partition aligned to 64k Have IOMeter Dynamo running on all eights VMs Use vcenter server as IOMeter Master Use IOMeter Access specification of 8K, 50% Write, 50% Random for all test cases Use Jumbo frames on the storage network Use flow control on the storage network Share the same file system for iscsi and NFS for these test cases Test parameters Our test will explore the details of implementation of datastore to the following scenarios and compares the IOMeter test results. NFS datastore Link aggregation Single storage subnet Two storage subnets Without link aggregation Single storage subnet Two storage subnets iscsi datastore Link aggregation Single storage subnet Two storage subnets Without link aggregation Single storage subnet Two storage subnets Applied Technology 11

12 NFS datastore link aggregation Introduction Link aggregation enables fault tolerance of NIC failures and also enables load balancing between multiple paths based on the policy. To use link aggregation: The Ethernet switches must support etherchannel or LACP. The Data Mover ports should be configured to use etherchannel or LACP. The virtual switch on the ESX servers should be configured to use IP-based load balancing. Single storage subnet NFS1 Step Action 1 Create multiple virtual interfaces on the Data Mover and assign IP on the same storage subnet. 2 Choose the IP address (destination IP) such that it can use different Data Mover interfaces for the same ESX IP address (source IP). It can be tested using the following command on the Cisco switch: test etherchannel load-balance interface <portchannel interface> ip <source ip> Applied Technology 12

13 <destination ip> 3 On the ESX server, create a VMKernel port and assign an IP address in the same storage subnet. Testing indicated that when multiple VMKernel ports were created in the same storage subnet, it only uses one to make the NFS connection. In the screen image above, you can see the TCP session information from the Celerra when the ESX server is connected to four NFS datastores on , and another four NFS datastores on Notice that there are two sessions per NFS datastore; one for data and another for control. 4 Access the NFS datastores using different IP address of the Data Mover. But, use the same IP that is used for the datastore on all ESX servers that access that datastore. Do not use Round Robin DNS for mounting the NFS datastore. Refer to VMware KB Article Refer to the NFS datastore troubleshooting section if the NFS datastore is not visible to the ESX server. Applied Technology 13

14 Two storage subnet NFS2 Step Action 1 Create the virtual interface and assign its IP addresses. We assigned two IPs per subnet to allow use of both Data Mover ports when accessing from the same ESX server. 2 Choose IP addresses such that the interface can use different ports for the same source address. It can be tested using test etherchannel command on the Cisco switch. 3 Access the NFS datastore using different the IP address of the Data Mover. Use the same IP that is used for the datastore on all ESX servers that are accessing that datastore. Do not use Round Robin DNS for mounting the NFS datastore. Refer VMware KB Article Refer to the NFS datastore troubleshooting section if the NFS datastore is not visible to the ESX server. Applied Technology 14

15 NFS datastore no link aggregation Introduction When the Ethernet switches do not support link aggregation, a failure of the Ethernet port in the path becomes noticeable and requires manual intervention to fix it. Even though we recommend link aggregation for NFS, we also tested it without link aggregation to check the effect on performance. Single storage subnet NFS3 Step Action 1 Assign the IP addresses on the same subnet to the Data Mover ports. 2 On the ESX server, create a VMKernel port and assign an IP address in the same storage subnet. Note: Even if you create multiple VMKernel ports in the same storage subnet, the server only uses one port for making the NFS connection. Applied Technology 15

16 In the screen image above, you can see the TCP session information from the Celerra when the ESX server is connected to four NFS datastores on , and to another four NFS datastores on Notice that there are two sessions per NFS datastore; one for data and another for control. If one of the NICs on the ESX goes down, it uses the other VMKernel port. 3 Access the NFS datastore using a different IP address of the Data Mover. Use the same IP that is used for the datastore on all ESX servers that access that datastore. Do not use Round Robin DNS for mounting the NFS datastore. Refer VMware KB Article Refer to the NFS datastore troubleshooting section if the NFS datastore is not visible to the ESX server. Applied Technology 16

17 Two storage subnet NFS4 Step Action 1 Assign two IP address for each Data Mover port on each subnet. 2 On the ESX server, create one VMKernel port per subnet. We created all the VMKernel ports for the NFS on the same vswitch. 3 Access the NFS datastore using a different IP address than the Data Mover. Use the same IP that is used for the datastore on all ESX servers that access that datastore. Do not use Round Robin DNS for mounting the NFS datastore. Refer VMware KB Article Refer to the NFS datastore troubleshooting section if the NFS datastore is not visible to the ESX server. Applied Technology 17

18 NFS performance results Introduction This topic describes the tested NFS datastore performance results for the following four scenarios: Link-Aggregation Single subnet NFS1 Two subnet NFS2 No Link-Aggregation Single subnet NFS3 Two subnet NFS4 The test was done using IOMeter with 8K, 50% write and 50% random workload. The test was run for 5 minutes after a 3-minutes ramp-up period. IOPS The following graph shows the IOPS comparison of the four test scenarios. The single subnet provided better IOPS, and performed best with link aggregation. Link aggregation also provides better fault tolerance for NFS datastores. Applied Technology 18

19 NFS datastore troubleshooting Introduction This topic discusses some basic troubleshooting steps to take if you have issues while accessing the NFS datastore on EMC Celerra. EMC Celerra Make sure the NFS service is started Check that the file system is mounted (with read/write option) using the Celerra CLI server_mount command Check that it is exported using the server_export CLI or using Celerra GUI Make sure you provided access to the VMKernel port IP address of ESX. Very often the service console IP address is mistakenly used instead of providing access to VMKernel IP. Check whether you provided the VMKernel port IP under the Root Hosts. You can list each individual host or provide access to the subnet address separated by : Applied Technology 19

20 The NFS communication with ESX can be verified using the server_netstat command. The speed, duplex, and flow control settings of the Data Mover ports can be verified using the command: server_sysconfig server_2 pci Applied Technology 20

21 If you are using Jumbo frames, they should be enabled throughout the data path. To check the MTU of the interface, use the server_ifconfig command or Celerra GUI. If you are using VLAN tagging, you can check or set it using the server_ifconfig command or using Celerra GUI. Check whether you can ping the ESX server s vmkernel port IP address from the Data Mover port. Use the server_ping cli command or the Celerra GUI. Applied Technology 21

22 Cisco switch Check that the ports are up. Verify that the ports are configured properly (ensure correct VLAN setting, link aggregation, and so on). Verify whether the switch can ping the Data Mover and ESX ports. Check the flow control (receive on) and Jumbo frame setting (if used). Test etherchannel and ensure it picks the right port. VMware ESX server Ensure VMkernel port is created on the correct vswitch. Check whether the vmkernel port is able to ping the Data Mover IP using the vmkping command. If link aggregation is in use, the vswitch load-balancing policy should be set to Route based on IP hash. If not, use Route based on the originating virtual port ID. If you are using Jumbo frames, it needs to be enabled on all ports of the NFS path. To verify or set VMKernel port setting, use the esxcfg-vmknic command. Applied Technology 22

23 If using a DNS alias for the NFS datastore, check whether the vmkernel is able to resolve it. You can test it using the vmkping command. It is not good if only the service console is able to resolve it. To troubleshoot NFS, temporarily portmap service and nfsclient can be enabled on the firewall. Use the following commands: service portmap start esxcfg-firewall e nfsclient Use the rpcinfo command to verify the NFS server is running NFS version 3 using TCP protocol. Ensure that ports UDP/TCP 111 and 2049 are opened if a firewall is used between the ESX and the Celerra. To verify the path that is used to mount the NFS datastore, use the showmount command. Applied Technology 23

24 To check the NFS statistics, use the vscsistats command and use esxtop or vcenter Client for network statistics. Use the esxcfg-nas command to manage the NFS datastore from the command line: esxcfg-nas l (to list the NFS datastore) esxcfg-nas a o s /NFS1 NFS1 (to add NFS datastore NFS1) esxcfg-nas d NFS1 (to delete the NFS datastore NFS1) Refer to VMware KB article and if you are using link aggregation and it is not load balanced properly. By default, ESX allows eight NFS datastores. To increase this number, modify the NFS.MaxVolumes advanced setting on each ESX host. Remember to increase the Net.TCPipHeapSize to 30 and Net.TCPipHeapMax to 120. Check the vmkernel logs for any evidence. Applied Technology 24

25 iscsi datastore link aggregation Introduction iscsi uses the SCSI protocol over Ethernet. Link aggregation provides fault tolerance for the Ethernet network. To use link aggregation: The Ethernet switches must support etherchannel or LACP. The Data Mover ports should be configured to use etherchannel or LACP. The virtual switch on the ESX servers should be configured to use Rout- based on IP hash. Single storage subnet iscsi1 Step Action 1 Create multiple virtual interfaces on the Data Mover and assign the IP addresses on same storage subnet. 2 Choose the IP address (destination IP) such that it can use different Data Mover interface for the same ESX IP address (source IP). You can test it using the following command on the Cisco switch: test etherchannel load-balance interface <portchannel interface> ip <source ip> Applied Technology 25

26 <destination ip> 3 Create the iscsi target with the Data Mover IPs created above in the network portal. 4 Assign iscsi LUNs to the target. 5 On the ESX server, create a VMKernel port and assign an IP address in the same storage subnet. We noticed that even if you create multiple VMKernel ports in the same storage subnet, it uses only one for iscsi session. In the screen image above, you can see the iscsi session information from /proc/scsi/iscsi_vmk/5. It is using a single IP address of the vmkernel and has established connections to both IPs of the Celerra. Usually, we can add the other NIC to the iscsi initiator using the esxcli command or vmkiscsi-tool command. To use that vmkernel port group, we should have only one active NIC assigned. With link aggregation, that won t be an option. This option created two paths per LUN. 6 Change Path selection policy to Round-Robin with 1 I/O per path. Note: Before changing any default parameters in your VMware environment, be sure to verify that the resulting configuration is supported by VMware. 7 Refer to the iscsi Datastore troubleshooting section for further tips. 8 Make sure the VM data disks are located on the iscsi datastore. If not, perform storage VMotion. Applied Technology 26

27 Two storage subnet iscsi2 Step Action 1 Create the virtual interface and assign its IP addresses. We assigned two IPs per subnet to allow utilization of both Data Mover ports when accessing from same ESX server. 2 Choose IP addresses such that it can use different ports for the same source address. It can be tested using the test etherchannel command on the Cisco switch. 3 On the ESX server, create one VMKernel port per subnet. We created all the VMKernel ports for the iscsi on the same vswitch. 4 In this example the iscsi session is established with both IPs of the iscsi vmkernel port. Applied Technology 27

28 This option created four paths per LUN. 6 Refer to the iscsi Datastore troubleshooting section for further suggestions. Applied Technology 28

29 iscsi datastore No link aggregation Introduction Because not all switches support link aggregation, the following test cases are executed without using the link aggregation feature of the switches, and using VMware NMP to load balance. Single Storage Subnet iscsi3 Step Action 1 Assign IP addresses on the same subnet as the Data Mover ports 2 Update the iscsi target to use the above network portal. 3 On the Ethernet switch, make sure no link aggregation is used. 4 Update the ESX to use round robin as the PSP for the Celerra iscsi devices. 5 Update the round robin policy to use one I/O per path. 6 On the ESX server, create a VMKernel port and assign an IP address in the same storage subnet. By default, it uses only one vmkernel port to connect to iscsi target. Applied Technology 29

30 To enable iscsi to use both ports, make sure the vmkernel port is using only one active NIC and that the other NICs are listed as unused. Then use the following commands: vmkiscsi-tool V a vmk1 vmhba33 and vmkiscsi-tool V a vmk2 vmhba33. This command is the same as using esxcli swiscsi nic add n vmk1 d vmhba33 and esxcli swiscsi nic add n vmk2 d vmhba33. Initially, it was having two paths per LUN. Then, after adding both NICs to the iscsi Applied Technology 30

31 initiator, it showed as six paths per LUN (two existing paths plus four new paths per LUN). After rebooting, it had only four paths per LUN as expected. 7 Refer to the iscsi Datastore troubleshooting section for further tips. Two storage subnet iscsi4 Step Action 1 Assign two IP address for each Data Mover port on each subnet. 2 Make sure the iscsi target contains the above network portals. 3 On the ESX server, create one VMKernel port per subnet. We created all the VMKernel ports for iscsi on the same vswitch. Assign the vmkernel ports to the iscsi initiator using vmkiscsi-tool or esxcli command. This option provides four paths per LUN. 4 Refer to the iscsi Datastore troubleshooting section for additional tips. Applied Technology 31

32 iscsi performance results Introduction This section describes the performance results of the tests we executed using the iscsi datastore in the following four scenarios. Link-Aggregation Single subnet iscsi1 Two subnet iscsi2 No Link-Aggregation Single subnet iscsi3 Two subnet iscsi4 The tests were done using IOMeter with 8K, 50% write and 50% random workload. The test for run for 5 minutes, after a 3 minutes ramp up period. IOPS The following graph shows the IOPS comparison fn the four test scenarios. Using two subnets provided better IOPS, and the best results were performed with etherchannel. Be aware that using etherchannel relies on the network, and the iscsi session won t be aware of any path failure. Applied Technology 32

33 iscsi datastore troubleshooting Introduction This section provides some of the basic troubleshooting steps to use if you have issues while accessing the iscsi datastore on EMC Celerra. EMC Celerra Make sure the iscsi service is started: From the Celerra console, run server_iscsi server_2 service -status To restrict the ESX server to view and login to its own iscsi targets, set the parameter SendTargetsMode to 1 using the server_param command. By default, Celerra will pass all the iscsi targets created. Verify the iscsi LUNs are granted access to the iscsi initiators using server_iscsi server_2 mask -list If using you are Jumbo frame, it should be enabled throughout the data path. To check the MTU of the interface, use the server_ifconfig command or Celerra GUI. If VLAN tagging is used, you can check or set it using the server_ifconfig command or using the Celerra GUI. Check pinging of the ESX server's vmkernel port ip address from the Data Mover port. This can be done using the server_ping cli command or using Celerra GUI. Cisco switch Check that the ports are up. Verify that the ports are configured properly (ensure correct VLAN setting, link aggregation, and so on). Verify whether it is able to ping the Data Mover and ESX ports. Check the flow control (receive on) and Jumbo frame setting (if used). Test etherchannel and ensure it picks the right port. Applied Technology 33

34 VMware ESX server Ensure that the VMkernel port is created on the correct vswitch. Check whether the vmkernel port is able to ping the Data Mover IP using the vmkping command If link aggregation is used, the load balancing policy of the vswitch should be set to Route based on IP hash. If not, use Route based on the originating virtual port ID Use esxcfg-mpath or the vcenter client to verify the path selection policy. Make sure it is set to Round Robin for EMC Celerra iscsi. To view the round robin policy, use the following command: esxcli nmp device list awk '/^naa/{print "esxcli nmp device setpolicy --device "$0" - -psp VMW_PSP_RR" };' Check the Round Robin policy to use one I/O per path using: esxcli nmp device list If not, the following command can be used to display the command that can set the policy to use one I/O per path. esxcli nmp device list aek /^naa/{print esxcli nmp roundrobin setconfig --device $0 --type IOPS --IOPS 1 }; To check the iscsi session information, first identify the SCSI controller number of iscsi HBA using: cat /proc/vmware/vmkstor and identify the SCSI number for the VMKernal HBA for iscsi controller. then, use: Applied Technology 34

35 cat /proc/scsi/iscsi_vmk/<scsi number> If you are using Jumbo frames, it must be enabled on all ports of the iscsi path. To verify or set VMKernel port setting, use the esxcfg-vmknic command. To check the Disk I/O statistics, use the vscsistats command or use esxtop or vcenter Client for further statistics. Refer to VMware KB article and if you are using link aggregation and it is not load balanced properly. Check the vmkwarning logs for any evidence. Applied Technology 35

36 Performance analysis Using one I/O per path The default policy will send 1000 IOs per path before switching the I/O to another path. If you are using one datastore, you will notice that the traffic is going through a single interface most of the time. We observed that changing the policy to use one I/O per path produced better throughput and utilized all of the paths. Note: Before changing any default parameters in your VMware environment, be sure to verify that the resulting configuration is supported by VMware. Applied Technology 36

37 Using PowerPath/VE with an EMC Celerra iscsi datastore With PowerPath/VE (b257), it didn t automatically claim the EMC Celerra iscsi datastore. PowerPath performed better than the default Round Robin policy on VMware, but produced similar results with modified round robin policy. With PowerPath/VE, we notice that the Least-I/O load-balancing policy (PP LI) produced better I/O than the default Adaptive load-balancing policy (PP AD) for our test workload. Applied Technology 37

38 PowerPath/VE load balancing policies PowerPath/VE offers the following load-balancing policies: Adaptive (default) Round Robin Streaming I/O Least Block Least I/O For our test workload with two storage subnets on a link aggregation network on a distributed switch, this is how each one performed. Applied Technology 38

39 Distributed switching Distributed switching makes it easier to deploy vsphere, compared to the standard vswitch. Distributed switching also helps in maintaining the network statistics during vmotion. What we observed is it produced similar results during our test. Applied Technology 39

40 Conclusion Summary VMware vsphere and EMC Celerra provide flexibility when choosing a storage protocol to meet a datastore's needs. Findings The following results were determined using the stated test plan and methodology: A single storage subnet in link aggregation provided better performance for an NFS datastore. There is no need to assign a NIC to the iscsi initiator when using link aggregation, and it is needed when not using link aggregation. Benefits Use the right topology and path selection policy to better achieve the performance and fault tolerance for the VMware vsphere storage network. Next steps EMC can help accelerate assessment, design, implementation, and management while lowering the implementation risks and cost of creating a virtualized data center. To learn more about this and other solutions contact an EMC representative or visit Applied Technology 40