Technical Report

Configuring and Installing the EqualLogic Multipathing Extension Module for VMware vSphere and PS Series SANs Abstract This Technical Report will explain the benefits of the EqualLogic Multipathing Extension Module (MEM) for VMware vSphere 5.x and 4.1 which provides multipath I/O for highly available access to the Dell EqualLogic PS Series SAN

TR1074

V1.3

Copyright 2013 Dell Inc. All Rights Reserved.

EqualLogic is a registered trademark of Dell Inc.

Dell is a trademark of Dell Inc.

All trademarks and registered trademarks mentioned herein are the property of their respective owners.

Information in this document is subject to change without notice.

Dell Inc. will not be held liable for technical or editorial errors or omissions contained herein. The information in this document is subject to change.

Reproduction in any manner whatsoever without the written permission of Dell is strictly prohibited.

Authored by: David Glynn

[September 2013]

WWW.DELL.COM/PSseries

Preface

PS Series arrays optimize resources by automating performance and network load balancing. Additionally, PS Series arrays offer all-inclusive array management software, host software, and free firmware updates.

Audience

The information in this guide is intended for administrators of VMware vSphere environment utilizing EqualLogic iSCSI arrays.

Related Documentation

For detailed information about PS Series arrays, groups, volumes, array software, and host software, log in to the Documentation page at the customer support site.

Dell Online Services

You can learn about Dell products and services using this procedure:

1. Visit http://www.dell.com or the URL specified in any Dell product information.

2. Use the locale menu or click on the link that specifies your country or region.

Dell EqualLogic Storage Solutions

To learn more about Dell EqualLogic products and new releases being planned, visit the Dell EqualLogic TechCenter site: http://delltechcenter.com/page/EqualLogic. Here you can also find articles, demos, online discussions, technical documentation, and more details about the benefits of our product family.

For an updated Dell EqualLogic compatibility list please visit the following URL: https://eqlsupport.dell.com/support/download.aspx?id=6442454231&langtype=1033

Table of Contents Revision Information ....................................................................................................................................... iii

Executive Summary .......................................................................................................................................... 1

Introduction ......................................................................................................................................................... 1

Deploying the EqualLogic MEM .................................................................................................................. 2

Deployment Considerations: Requirements .................................................................... 2 Deployment Considerations: Storage Heartbeat on vSphere 5.0 and 4.1 ........ 2 Deployment Considerations: iSCSI Connection Count ............................................. 3 Deployment Considerations: iSCSI Login Timeout on vSphere 5.x .................... 4 Deployment Considerations: Best Practices parameter in MEM 1.2.................... 5

Configuring an iSCSI vSwitch for Multipathing .................................................................................... 6

Interactive Mode configuration .............................................................................................. 6 Unattended Mode configuration ............................................................................................ 8

Installing the EqualLogic MEM ..................................................................................................................... 9

Verification of MEM iSCSI Session Creation ........................................................................................ 10

Advanced iSCSI connection configuration parameters ................................................................. 11

Increasing the default values ................................................................................................. 11 Decreasing the default values ................................................................................................ 12 Setting the EHCM configuration values under vSphere 5.x ................................... 13 Setting the EHCM configuration values under vSphere 4.1 ................................... 13

Summary ............................................................................................................................................................. 14

Technical Support and Customer Service ............................................................................................ 14

Appendix A: Example iSCSI vSwitch configurations ........................................................................15

Overriding hardware iSCSI offload default utilization ............................................... 15 Utilizing a vNetwork Distributed Switch .......................................................................... 15 Enabling Jumbo Frames ........................................................................................................... 15 Setting the iSCSI discover address....................................................................................... 15

Appendix B: Installing the MEM with VMware Update Manager ................................................ 16

iii

Revision Information The following table describes the release history of this Technical Report.

Report Date Document Revision

1.0 November 2011 Initial Release

1.1 February 2012 General Availability updates

1.2 September 2012 Updated Storage Heartbeat recommendation for vSphere 5.1

1.3 September 2013 Updated to reflect firmware 6.0 and vSphere 5.5

The following table shows the software and firmware used for the preparation of this Technical Report.

Vendor Model Software Revision

VMware vSphere 4.1 or 5.x with Enterprise licensing 4.1 or 5.x

Dell Dell EqualLogic PS Series SAN 4.3 or above

Dell EqualLogic Multipathing Extension Module for VMware vSphere 5.x

1.2

Dell EqualLogic Multipathing Extension Module for VMware vSphere 4.1

1.1.1

The following table lists the documents referred to in this Technical Report. All PS Series Technical Reports are available on the Customer Support site at: support.dell.com

Vendor Document Title

Dell Dell EqualLogic PS Series Array Administration Guide

Dell EqualLogic Multipathing Extension Module: Installation and User Guide

VMware vSphere Storage Guide

VMware vSphere Installation and Setup Guide

VMware Installing and Administering VMware vSphere Update Manager

VMware vSphere Command-Line Interface Concepts and Examples

VMware vSphere Management Assistant Guide

CONVENTIONS Throughout this document the term ESXi is used to refer to both ESX and ESXi hypervisors. The EqualLogic MEM is supported on vSphere 4.1 ESX and ESXi, and vSphere 5.x ESXi hypervisor platforms with Enterprise or Enterprise Plus licensing.

1

Executive Summary High availability is an important requirement of any system in the datacenter. This availability is even more critical if that system is a component in the virtual infrastructure upon which a virtualized datacenter is built. Redundant hardware and RAID technologies form a critical foundation. When using shared storage, the paths from the servers to the storage need to also be redundant and highly available.

This Technical Report details the benefits of Dells EqualLogic Multipathing Extension Module, MEM, for VMware vSphere, as well the installation and configuration process to provide multipath I/O for high available access to the Dell EqualLogic PS Series SAN. Also covered are a number of overall virtual environment iSCSI design considerations and best practices.

Introduction VMware vSphere offers many enhancements to the software iSCSI initiator beyond basic iSCSI SAN connectivity. The most significant of these enhancements is the API support for third party mutipathing plugins. This provides a framework that enables the EqualLogic MEM to intelligently route and efficiently load balance iSCSI traffic across multiple NICs.

The EqualLogic MEM provides the following benefits:

Ease of install Increased bandwidth Reduced network latency Automatic failure detection and failover Automatic load balancing across multiple active paths Automatic connection management Multiple connections to a single iSCSI target

The EqualLogic MEM utilizes the same multipathing iSCSI vSwitch as VMwares Round Robin multipathing. As part of Dells continuous efforts to help customers simplify the configuration of their IT environments, the iSCSI MPIO vSwitch configuration process for the EqualLogic MEM has been reduced to either a single command with a few parameters or a guided question and answer process. The MEM installation process is equally straightforward, requiring that only a single command be executed. The MEM can also be installed using VMwares vSphere Update Manager.

Once installed, the EqualLogic MEM will automatically create iSCSI sessions to each member that a volume spans. As the storage environment changes, the MEM will respond by automatically adding or removing iSCSI sessions as needed.

As storage I/O requests are generated on the ESXi hosts, the MEM will intelligently route these requests to the array member best suited to handle the request. This results in efficient load balancing of the iSCSI storage traffic, reduced network latency and increased bandwidth.

2

Deploying the EqualLogic MEM Deploying the EqualLogic MEM consists of two steps:

Configuring a vSwitch for iSCSI multipathing Installing the EqualLogic MEM

The entire process of creating the multipathing compatible vSwitch and installing the EqualLogic multipathing extension module can be quickly and efficiently completed. Once deployed, it can provide both new and existing ESXi hosts with increased performance to EqualLogic storage resources.

Deployment Considerations: Requirements

The EqualLogic MEM has the following requirements:

VMware vSphere ESXi 4.1 or 5.x with Enterprise or Enterprise Plus licensing VMware CLI (Command-Line Interface) or VMware vMA (vSphere

Management Assistant) compatible with above version of ESXi Compatible EqualLogic array firmware, refer to Release Notes.

Prior to deploying the MEM the following steps should be completed:

1. The ESXi host(s) must be placed in maintenance mode. 2. Download and install either the VMware vMA, or vSphere CLI. Refer to

VMwares documentation for installation and configuration details of these tools.

3. Download the Dell EqualLogic Multipathing Extension Module for VMware vSphere (MEM) from the EqualLogic Support website. There are currently two version of MEM; MEM 1.2 which supports versions 5.0, 5.1 and 5.5 of ESXi, and MEM 1.1.2 which supports versions 4.1, 5.0 and 5.1 of ESXi. Customers are encouraged to use the most current applicable version for the version of ESXi they are using. The download will be a zip archive named EqualLogic-ESX-Multipathing-Module.zip

4. Unpack the ZIP archive. It will contain the files: dell-eql-mem-esx-.zip

Note: This is a VIB offline bundle and should not be unzipped.

MEM-Release_Notes.pdf MEM-User_Guide.pdf README.txt setup.pl

5. If using the vMA, upload setup.pl and the VIB offline bundle to the vMA. 6. Retain the MEM-Release_Notes.pdf, MEM-User_Guide.pdf, and README.txt

files for reference.

Note: MEM 1.2 is only compatible with vSphere 5.x and certified on EqualLogic firmware version 5.2. For prior versions of vSphere or firmware use MEM 1.1.x.

Deployment Considerations: Storage Heartbeat on vSphere 5.0 and 4.1

In the VMware virtual networking model, certain types of vmkernel network traffic are sent out a default vmkernel port for each subnet. The iSCSI multipathing network

3

configuration requires that the iSCSI vmkernel ports use a single physical NIC as an uplink. As a result, if the physical NIC that is being used as the uplink for the default vmkernel port goes down, network traffic that is using the default vmkernel port will fail. This includes vMotion traffic, SSH access, and ICMP ping replies.

Though iSCSI traffic isnt directly affected by this condition, a side effect of the suppressed ping replies is that the EqualLogic PS Series group will not be able to accurately determine connectivity during the login process, and therefore a suboptimal placement of iSCSI sessions will occur. In some scenarios, depending upon array, server and network load, logins may not be completed in a timely manner. To prevent this from occurring, Dell recommends that a highly available vmkernel port be created on the iSCSI subnet serving as the default vmkernel port for such outgoing traffic.

Note: This recommendation for using Storage Heartbeat applies only to vSphere 4.1 and 5.0. It is not necessary with the improvements in vSphere 5.1 and later.

Deployment Considerations: iSCSI Connection Count

The Dell EqualLogic MEM provides for increased bandwidth and lower latency access to EqualLogic storage. This performance benefit is achieved through leveraging several behaviors that are unique to the EqualLogic peer storage architecture. It is important to understand how the MEM achieves these performance gains, and the potential impact it can have if these considerations are not taken into account.

The MEM achieves its performance gains by creating multiple iSCSI connections to each PS Series group member on which a datastore volume resides. Assuming the MEMs default settings are in use, and depending on the configuration of the environment, there will be up to six iSCSI connections to a datastore volume. This is a significant increase, when compared with VMwares Fixed Path policy, which utilizes one iSCSI connection per volume. This increase in connections must be planned for at deployment time, and also, as the vSphere environment and its supporting EqualLogic storage environment scales.

To calculate the number of iSCSI connections that the MEM will consume in a particular environment, utilize the following formula:

Number of ESXi hosts * 2 (default iSCSI sessions per volume portion) * Number of EqualLogic members in the pool (with a max value of 3) * Number of volumes

For example: In a vSphere environment with eight ESXi hosts, and using a two member EqualLogic pool for hosting the ten volumes needed for virtual machines this would be:

8 * 2 * 2 * 10 = 320 iSCSI connections

While this is within the 1024 iSCSI connection limit per pool of the firmware, it does not take into account other iSCSI connections to the EqualLogic storage pool from other servers in the datacenter. Consideration should also be given to how this virtual environment may grow in the future with respect to additional ESXi hosts, datastore volumes and additional EqualLogic members.

4

The release of EqualLogic 6.0 firmware provided for enhanced communication with the MEM. This enables the array to notify the MEM of the number of total iSCSI connections to the pool from all sources. Should the number of iSCSI connections to the pool begin to approach the limit, then the MEM will reduce the number of iSCSI session it is creating to the array, while still maintaining redundancy.Depending on the overall environment, and future requirements, changes may need to be made to one or more of the following if there are concerns about the iSCSI connection count growing too large:

The MEM parameters membersessions, volumessessions or totalsessions: see the Installation and User Guide for details.

The number of volumes: By increasing the size of a given volume, more virtual machines can reside on it, thereby reducing the total number of volumes needed. With vSphere 5.0 datastore size is no longer restricted to 2TB.

Reconfigure larger clusters into multiple smaller clusters. By splitting large clusters into smaller clusters, the number of hosts accessing particular volumes is reduced, thereby reducing the number of iSCSI connections consumed.

The configuration of EqualLogic members: reducing the number of EqualLogic members per pool, and increasing the number of pools, will increase the number of available iSCSI connections.

For more information on this topic read TR1072 Dell EqualLogic PS Arrays Scalability and Growth in Virtual Environments http://en.community.dell.com/dell-groups/dtcmedia/m/mediagallery/19992296.aspx

As with all rules there are exceptions. The MEM iSCSI connection algorithm works to avoid creating unnecessary sessions while still maintaining redundancy. With the PS6110 and PS-M4110, both of which have only one 10Gb Ethernet port, this results in fewer iSCSI connections being created when compared to arrays with multiple Ethernet ports per controller. With the PS6110 and PS-M4110, if they are in a single member pool, MEM will create two iSCSI connections per volume, for redundancy. In a two or three member pool MEM will create a single iSCSI connection per member, resulting in a total of two or three iSCSI connections being created per volume. This balances the bandwidth and throughput from an individual ESXi host with that of an individual EqualLogic member.

Deployment Considerations: iSCSI Login Timeout on vSphere 5.x

The default value of 5 seconds for iSCSI logins on vSphere 5.x is too short in some circumstances. For example: In a large configuration where the number of iSCSI sessions to the array is close to the limit of 1024 per pool. If a severe network disruption were to occur, such as the loss of a network switch, a large number of iSCSI sessions will need to be reestablished. With such a large number of logins occurring, some logins will not be completely processed within the 5 second default timeout period.

Dell therefore recommends applying patch ESXi500-201112001 and increasing the ESXi 5.0 iSCSI Login Timeout to 60 seconds to provide the maximum amount of time for such large numbers of logins to occur.

5

If the patch is installed prior to installing the EqualLogic MEM, the MEM installer will automatically set the iSCSI Login Timeout to the Dell recommended value of 60 seconds.

The iSCSI Login Timeout value can also be set using esxcli with the following syntax:

esxcli iscsi adapter param set --adapter=vmhba --key=LoginTimeout --value=60 See VMware KB 2009330 for additional information.

Deployment Considerations: Best Practices parameter in MEM 1.2

One of the new options in version 1.2 of MEMs setup.pl script for configuring the ESXi hosts iSCSI vSwitch is the --bestpractice parameter. Using this parameter will change some of the ESXi hosts settings from the defaults.

With the MEM 1.2 release the settings that are changed are:

Disabling Delayed ACK: Delayed ACK is a TCP/IP method of allowing segment acknowledgements to piggyback on each other or other data passed over a connection with the goal of reducing IO overhead. One side effect of delayed ACK is that if the pipeline isnt filled, acknowledgement of data will be delayed. In SANHQ this can be seen as higher latency during lower I/O periods. Latency is measured from the time the data is sent to when the acknowledgement is received. Since we are talking about disk I/O any increase in latency can result in poorer performance. Additional information can be found in VMware KB 1002598.

Note: While iSCSI Login Timeout is considered a best practice, it is also consider a requirement, and therefore will always be set to 60 seconds during installation.

6

Configuring an iSCSI vSwitch for Multipathing As previously mentioned, the EqualLogic MEM utilizes the same multipathing vSwitch as VMwares Round Robin multipathing. Therefore if the ESXi hosts are already configured for Round Robin this step can be omitted. However, if the ESXi hosts are configured for Fixed Path, the iSCSI initiator and associated vSwitch should be removed before continuing. Those who have previously configured Round Robin multipathing will appreciate the powerful functionality and the ease of use the MEMs setup.pl script provides when compared to the manual configuration process.

Note: The instructions provided here refer to using the vMA, however the syntax is the same whether the vMA or CLI is used. The optional parameters --username and --password have been excluded from the examples below for clarity. If not included and vi-fastpass is not configured, then the user will be prompted to provide the username and password.

1. Connect to the vMA and change directory to where the setup.pl was uploaded to.

2. The simplest method of creating a multipathing iSCSI vSwitch is to invoke the setup.pl in Interactive Mode.

setup.pl --configure --server=hostname In this configuration mode a series of questions are posed to the user, and in many instances default options presented. To accept a default, press enter, as shown in the example below:

Interactive Mode configuration

setup.pl --configure --server=10.124.6.223 Do you wish to use a standard vSwitch or a vNetwork Distributed Switch (vSwitch/vDS) [vSwitch]: Found existing switches vSwitch0. vSwitch Name [vSwitchISCSI]: Which nics do you wish to use for iSCSI traffic? [vmnic1 vmnic2 vmnic3]: vmnic2 vmnic3 IP address for vmknic using nic vmnic2: 192.168.0.215 IP address for vmknic using nic vmnic3: 192.168.0.216 What IP address would you like to use for the highly available heartbeat vmknic (optional)?: 192.168.0.214 Netmask for all vmknics [255.255.255.0]: What MTU do you wish to use for iSCSI vSwitches and vmknics? Before increasing the MTU, verify the setting is supported by your NICs and network switches. [1500]: 9000 What prefix should be used when creating VMKernel Portgroups? [iSCSI]: The SW iSCSI initiator is not enabled, do you wish to enable it? [yes]: What PS Group IP address would you like to add as a Send Target discovery address (optional)?: 192.168.0.200 What CHAP user would you like to use to connect to volumes on this group (optional)?: BLUEcluster What CHAP secret would you like to use to connect to volumes on this group (optional)?:

7

Configuring iSCSI networking with following settings: Using a standard vSwitch 'vSwitchISCSI' Using NICs 'vmnic2,vmnic3' Using IP addresses '192.168.0.215,192.168.0.216' Creating a highly available vmkernel port with IP '192.168.0.214' Using netmask '255.255.255.0' Using MTU '9000' Using prefix 'iSCSI' for VMKernel Portgroups Using SW iSCSI initiator Enabling SW iSCSI initiator Adding PS Series Group IP '192.168.0.200' with CHAP user 'CHAPuser' to Send Targets discovery list. The following command line can be used to perform this configuration: setup.pl --configure --server=10.124.6.223 --vswitch=vSwitchISCSI --mtu=9000 --nics=vmnic2,vmnic3 --ips=192.168.0.215,192.168.0.216 --heartbeat=192.168.0.214 --netmask=255.255.255.0 --vmkernel=iSCSI --nohwiscsi --enableswiscsi --groupip=192.168.0.200 --chapuser=BLUEcluster Do you wish to proceed with configuration? [yes]:

Note that the CHAP secret is not displayed as part of the command line that Interactive Mode will generate.

3. As the script executes, it will provide status notifications as it proceeds through several steps to create the multipathing iSCSI vSwitch.

4. Once complete a multipathing iSCSI vSwitch, like the example shown below, will be created on the ESXi host.

A detailed list of all the parameters options and their usage can be found in the EqualLogic MEM Installation and User Guide. Additional configuration examples can be found in Appendix A.

Note: The example above was generated using MEM 1.1.1 and vSphere 5.1, the output may differ slightly with other combinations.

8

Unattended Mode configuration

While setup.pl scripts Interactive Mode is extremely helpful, using it to configure all the hosts in a cluster is not the most efficient means of performing this task. Instead it is possible to pass to the setup.pl script the values for the various parameters.

At the end of the Interactive Mode configuration shown above, it presents the resulting command line from the Interactive Mode questions and answers. This is shown again here:

setup.pl --configure --server=10.124.6.223 --vswitch=vSwitchISCSI --mtu=9000 --nics=vmnic2,vmnic3 --ips=192.168.0.215,192.168.0.216 --heartbeat=192.168.0.214 --netmask=255.255.255.0 --vmkernel=iSCSI --nohwiscsi --enableswiscsi --groupip=192.168.0.200 --chapuser=BLUEcluster

Using this as an example, and by modifying the hostname and IP information additional ESXi hosts can be easily provisioned with the same vSwitch configuration. For example:

setup.pl --configure --server=10.124.6.224 --vswitch=vSwitchISCSI --mtu=9000 --nics=vmnic2,vmnic3 --ips=192.168.0.225,192.168.0.226 --heartbeat=192.168.0.224 --netmask=255.255.255.0 --vmkernel=iSCSI --nohwiscsi --enableswiscsi --groupip=192.168.0.200 --chapuser=BLUEcluster --chapsecret=BLUEsecret Note that the CHAP secret is not displayed as part of the command line that Interactive Mode generates, but has been added to the example above. If not included, setup.pl will prompt for the secret at run time. Depending upon the required configuration of the multipathing iSCSI vSwitch additional parameters maybe required or removed. For a full listing of the parameters and their defaults see the Configuring Your Network for the MEM Plugin in the Dell EqualLogic MEM Installation and User Guide.

9

Installing the EqualLogic MEM The EqualLogic MEM can be installed using the command line tools, CLI or vMA, or with VMware Update Manager (VUM). The command line tools are used in this example. See Appendix C for install instructions on using VUM for installation.

Setup.pl is a Perl script wrapper around a number of VMware CLI commands, and hence provides administrators with a similar installation process regardless of vSphere version. However there are some differences, which are listed here:

On vSphere 5.x:

The multipathing functionality is available immediately after a fresh install; however hostd needs to be restarted prior to the new esxcli controlling and reporting commands being available.

Prior to installation setup.pl will copy the VIB to the first datastore it finds; optionally a particular datastore can be specified by using the --datastore parameter. Due to API limitations the VIB is not deleted by setup.pl.

On vSphere 4.1:

A reboot is required before the plugins multipathing functionality is available.

Note: When performing an upgrade or uninstall of the MEM a reboot is required on all versions of vSphere.

1. Using the vMA or vSphere CLI, execute the following command for each host the MEM is to be installed to:

setup.pl --install --server=hostname It may take a few minutes to install the module to the ESXi host.

2. Depending on the version of vSphere this next step will differ: a. On a vSphere 5.x host, the plugins multipathing functionality is available

for use.

To enable of the new esxcli commands restart the hostd service by executing the following command issued on the host, as documented in VMware KB2004078:

/etc/init.d/hostd restart b. On a vSphere 4.1 host, a reboot is required before the plugins

multipathing functionality is available. To automatically reboot the ESXi host once the install is complete include the --reboot parameter.

3. To verify the availability of a the EqualLogic MEM execute: vSphere 5.x: esxcli storage nmp psp list vSphere 4.1: esxcli nmp psp list

This will display a list of the PSP installed on the host, as shown below:

Name Description DELL_PSP_EQL_ROUTED Dell EqualLogic Path Selection VMW_PSP_MRU Most Recently Used Path Selection VMW_PSP_RR Round Robin Path Selection VMW_PSP_FIXED Fixed Path Selection

10

Verification of MEM iSCSI Session Creation By default the EqualLogic MEM will claim any existing and new EqualLogic volumes and create the additional iSCSI session used by the MEM to route the iSCSI data. To verify these additional sessions, perform the following steps:

1. In the vSphere client click on the Configuration tab. In the Hardware pane select Storage.

2. Right click on the datastore, select Properties, and then click the Managed Paths button.

3. In the example above the Path Selection Policy has been set to use the MEM, as path selection shows DELL_PSP_EQL_ROUTED. Four sessions to the volume have been created, as the volume resides in a two member storage pool.

4. This can also be verified from the array web GUI by clicking on the volumes Connections tab. As shown in the example below, two iSCSI sessions have been established from each of the VMkernel Ports on the ESXi host to the volume.

11

Advanced iSCSI connection configuration parameters There are minimal configuration parameters that are needed with the EqualLogic MEM. The few that do exist are used to alter the runtime behavior of the EqualLogic Host Connection Manager, EHCM, which manages the iSCSI sessions to the EqualLogic volumes. For information on all parameters refer to the Dell EqualLogic MEM Installation and User Guide.

Three configuration parameters affect the number of iSCSI sessions that will be created:

totalsessions: The maximum total number of session that may be created to all EqualLogic volumes that the host can access. Default value: 512

volumesessions: The maximum number of session that may be created to any individual EqualLogic volume. Default value: 6

membersessions: The maximum number of session that may be created to the portion of a volume that resides on a single member. Default value: 2

When determining how many sessions to create, EHCM chooses a value that meets all these constraints. The default values were chosen to provide good performance without unnecessarily consuming excess resources. In the majority of installations, these settings do not need to be changed from the defaults.

Prior to altering these values it is strongly advised that an administrator fully understand the impact of such a change on the total number of iSCSI connections. For information on the number of iSCSI connections that particular firmware versions can handle at a per pool and group level, refer to the release notes for that firmware. Refer to VMwares documentation for details on vSphere limits that may apply.

The Deployment Considerations: iSCSI Connection Count section of this technical report includes a formula for calculating the iSCSI connection count based on the number of hosts, sessions per volume portion, EqualLogic members in the pool, and the number of volumes the hosts are connected to. One should also take into account connections from other systems such as; other physical servers, virtual machines with iSCSI within the guest connections, and backup servers, as well as short lived connections used by xcopy, which is used by the vSphere VAAI Full Copy primitive and replication, in the total iSCSI connection count.

Increasing the default values

In some instances there may be a preference to increase the number of iSCSI connections. Typically these preferences only exist in lab settings, where the desire is to benchmark I/O to an individual volume or in other ways test the limits.

In such a configuration it is possible that the default membersession value is limiting the number of iSCSI connections to fewer then the number of VMkernel ports bound to the iSCSI initiator. To utilize all the VMkernel ports bound to the iSCSI initiator, membersessions should be increased to a sufficiently high value to enable EHCM to create iSCSI connections through all bound VMkernel ports.

Generally this increase would not be beneficial in a production environment. In a production environment multiple volumes are used, and EHCM would, in aggregate,

12

create and balance an optimal number of iSCSI sessions, effectively utilize all of the network ports

Decreasing the default values

In large configurations it is possible to exceed the iSCSI connection limits of the array firmware. In such cases it is necessary to reduce the number of iSCSI connections to be within limits. This can be achieved in several ways including:

Reduce the number of volumes: By increasing the size of a given volume, more virtual machines can reside on it, thereby reducing the total number of volumes needed. With vSphere 5.0 datastore are no longer restricted to 2TB.

Reconfigure larger clusters into multiple smaller clusters. By splitting a large cluster into smaller clusters, the number of hosts accessing particular volumes is reduced, thereby reducing the number of iSCSI connections consumed.

Alter the configuration of EqualLogic group: reducing the number of EqualLogic members per pool, and increasing the number of pools, will increase the number of available iSCSI connections.

However, these changes typically take some time to implement. Altering the EHCM parameters provides a means of quickly reducing the iSCSI connection to be within limits. However, depending on the overall environment configuration and I/O workload, a drop in overall performance may be observed.

totalsessions: This parameter is defaulted to a maximum of 512, and can be lowered to 64. It is the maximum number of iSCSI connections that EHCM will create from this individual ESXi host to all EqualLogic arrays. If an additional volume is added to the host EHCM will automatically rebalance the sessions to include the new and existing volumes, yet not consume more than the totalsessions limit.

volumesessions: This parameter is defaulted to a maximum of 6, and can be lowered to 1. It is the maximum number of iSCSI connections that EHCM will make from this individual ESXi host to each individual EqualLogic volume, regardless of the number of array members the volume may span as the group expands. This value applies to all volumes that the host accesses, and cannot be specified to affect only particular volumes. As additional members are added to the pool, and volumes are distributed to include this new member, EHCM will create additional sessions to the volume within this limit.

membersessions: This parameter is defaulted to a maximum of 2, and can be lowered to 1. It is the number of iSCSI connections that EHCM will make from this individual ESXi host to the portion of a volume that resides on an individual EqualLogic member. Setting membersessions to 1 will halve the iSCSI connection count from the ESXi host to the array. However, this effectively disables the Least Queue Depth part of the MPIO algorithm, as there is one queue to each portion of the volume to choose from. The Intelligent Routing part of the algorithm remains in use, so I/O requests will be efficiently directed to the appropriate member.

13

Setting the EHCM configuration values under vSphere 5.x

For vSphere 5.0 EqualLogic have added to the existing esxcli command set a number of commands that can be used to control and report on the status of the MEM. It is through these commands that the EHCM parameters are changed.

esxcli can be executed remotely from the vMA, CLI, or directly on the ESXi host

The syntax of this command is:

esxcli equallogic param set --name=parameter_name --value=parameter_value

For example:

esxcli equallogic param set --name=membersession --value=1 To query the current EHCM values use the following syntax:

esxcli equallogic param list

Setting the EHCM configuration values under vSphere 4.1

For vSphere 4.1 the setup.pl script is used to change and query the EHCM configuration values. It can be executed from the vMA or CLI, but not directly on the ESXi host.

The syntax of this command is:

setup.pl --setparam --name=parameter_name --value=parameter_value --server=hostname

For example:

setup.pl --setparam --name= membersesion --value=1 --server=hostname

To query the current EHCM values use the following syntax:

setup.pl --listparam --server=hostname

14

Summary The EqualLogic MEM, through its intelligent routing and load balancing, can provide a reduction in network latency and an increase in bandwidth to PS Series Storage arrays. Through automated setup and host connection management, the MEM also reduces the steps for deployment and ongoing management of advanced vSphere iSCSI configurations.

Technical Support and Customer Service

Dell support service is available to answer your questions about PS Series SAN arrays.

Contacting Dell

1. If you have an Express Service Code, have it ready. The code helps the Dell automated support telephone system direct your call more efficiently.

2. If you are a customer in the United States or Canada in need of technical support, call 1-800-945-3355. If not, go to Step 3.

3. Visit support.dell.com/equallogic.

4. Log in, or click Create Account to request a new support account.

5. At the top right, click Contact Us, and call the phone number or select the link for the type of support you need.

15

Appendix A: Example iSCSI vSwitch configurations This appendix provides some examples of the additional parameters used with the setup.pl configuration script. A detailed list of all the parameters and their usage can be found in the EqualLogic MEM Installation and User Guide

Overriding hardware iSCSI offload default utilization

With vSphere 4.1 and above, ESXi can utilize the iSCSI offload capabilities of the Broadcom NetXtreme II network adaptors, resulting in significantly lower software iSCSI CPU utilization. The setup.pl configuration script will, by default, utilize this iSCSI offload capability if it is present. If there is a preference not to use the iSCSI offload capability this must be specified when configuring the iSCSI vSwitch. This is shown below:

setup.pl --configure --server=172.17.5.121 --nics=vmnic2,vmnic3 --ips=192.168.0.215,192.168.0.216 --nohwiscsi

Utilizing a vNetwork Distributed Switch

With Enterprise Plus licensing VMware provides a virtual switch which spans many ESXi hosts. This abstracts the configuration of individual vSwitches on the host level and enables centralized management through vSphere vCenter Server. If utilizing a vNetwork Distributed Switch for iSCSI traffic the --vds parameter must be specified. Should the name of the vNetwork Distributed Switch differ from the default utilized by the configuration script, it can be specified using the -vswitch parameter. This is shown below:

setup.pl --configure --server=172.17.5.121 --nics=vmnic2,vmnic3 --ips=192.168.0.215,192.168.0.216 -vswitch vdsISCSI --vds

Enabling Jumbo Frames

With the vSphere release of ESXi support for Jumbo Frames has been extended to VMkernel traffic, which includes the iSCSI stack. To utilize Jumbo Frames they must be enabled on all networking components used. By default the setup.pl script uses an MTU of 1500 when creating the iSCSI vSwitch and VMkernel interfaces. To use a larger value specify it as demonstrated in the example below.

setup.pl --configure --server=172.17.5.121 --nics=vmnic2,vmnic3 --ips=192.168.0.215,192.168.0.216 -mtu=9000

Setting the iSCSI discover address

It is possible to specify the group IP of an array to be set as the Send Targets discovery address for the iSCSI initiator.

setup.pl --configure --server=172.17.5.121 --nics=vmnic2,vmnic3 --ips=192.168.0.215,192.168.0.216 -groupip=192.168.0.200

16

Appendix B: Installing the MEM with VMware Update Manager VMware Update Manager has the ability to install and upgrade third party packages to the ESXi hosts. This enables administrators to not only manage the patching and updating of ESXi hosts but also to update third party packages installed on the ESXi hosts. Installing the MEM consists of four major steps: Steps 1-3 need to be done once per version release of the MEM

o Importing the MEM to the Patch Repository o Creating an extension baseline that includes the MEM o Attaching the baseline to the environment

Step 4 needs to be done for each host in the cluster, or datacenter o Installing the MEM to each host

Step 1: Importing the MEM to the Patch Repository

1. Download Dells EqualLogic MEM from the EqualLogic Support website. 2. Unpack the ZIP archive. Do not unpack the embedded zip file, this is a VIB

offline bundle and is expected to be in this format. 3. From the vSphere client Home section, select Update Manager from under

Solutions and Applications. 4. From the Admin View select the Patch Repository tab and then click on

Import Patches to start the Import Patches wizard. 5. Click on Browse and browse to where the Zip archive was unpacked and

select the embedded Zip file named dell-eql-mem-.zip, click Open and then click Next.

6. The Import Patches wizard will upload and analyze the file; this may take a few minutes, and will then present a Confirm Import page. Verify the details are as expected and click Finish.

Step 2: Creating an Extension Baseline

7. From the vSphere client select Update Manager -> Admin View and select the Baselines and Groups tab.

8. On the Baselines and Group tab, in the Baseline section, click Create to start the New Baseline wizard.

17

9. Provide the baseline with a suitable name and optional description, select the baseline type Host Extension and then click Next, as shown in the example below.

10. From the list of extensions, highlight the Dell EqualLogic iSCSI MEM 1.1.0, click the selection button and then click Next. If there are a large number of extensions in the repository, use EqualLogic as a keyword for filtering.

11. On the Ready to Complete page of the wizard verify that the information is correct, and click Finish.

Step 3: Attaching the Extension Baseline

12. From the vSphere client select Update Manager -> Compliance View. 13. From the tree pane, on the left, select the Datacenter, Cluster, or Host that

the MEM Extension Baseline is to be attached to, and then click on Attach to start the Attach Baseline wizard.

14. Select the MEM extension baseline created above and click on Attach to attach the Extension Baseline to the vSphere Datacenter, Cluster or Host.

Step 4: Installing the MEM

15. From the vSphere client select Update Manager -> Compliance View. 16. In the Attached Baselines pane highlight the MEM extension baseline that

was attached earlier and click the Remediate button to start the Remediation wizard.

17. On the Remediation Selection page of the wizard verify that the correct baseline is listed, and unselect any host to which the EqualLogic MEM is not to be installed to at this time. Click Next to continue.

18. The Patches and Extensions page lists the patches and extensions to be applied. Click Next to continue.

18

19. On the Schedule page change the Task Name, if desired, and optionally provide a Task Description. There is also the option to schedule the deployment for a future time and date, rather than Immediately which is selected by default. Click Next to continue.

20. On the Host Remediation Options and Cluster Remediation Options pages there are options for altering the behaviors of the virtual machines, hosts, and cluster during the install. Refer to the vCenter Update Manager Installation and Administration Guide for details. Click Next to continue.

21. On the Ready to Complete page, verify that the information is correct, and click Finish. Unless the task was schedule to run at a later time it will be immediately executed.

22. As the task is been executed it will display status updates in the Recent Tasks pane of the vSphere client. If several host were selected the task will execute against one host at a time, until the MEM has been installed on all the selected hosts.

23. Once the task has been completed the MEM will have been installed or updated on all the hosts selected.

24. As shown in the screenshot below, the vCenter Update Manager can provide a clear graphical view of which ESXi hosts the MEM is installed or updated on, and which hosts it has yet to be installed or updated on.

Note: vCenter Update Manager is only capable of install the MEM. vMA or vCLI will need to be utilized to configure the iSCSI vSwitch for the MEM.

Revision InformationExecutive SummaryIntroductionDeploying the EqualLogic MEMDeployment Considerations: RequirementsDeployment Considerations: Storage Heartbeat on vSphere 5.0 and 4.1Deployment Considerations: iSCSI Connection CountDeployment Considerations: iSCSI Login Timeout on vSphere 5.xDeployment Considerations: Best Practices parameter in MEM 1.2

Configuring an iSCSI vSwitch for MultipathingInteractive Mode configurationUnattended Mode configuration

Installing the EqualLogic MEMVerification of MEM iSCSI Session CreationAdvanced iSCSI connection configuration parametersIncreasing the default valuesDecreasing the default valuesSetting the EHCM configuration values under vSphere 5.xSetting the EHCM configuration values under vSphere 4.1

SummaryTechnical Support and Customer ServiceAppendix A: Example iSCSI vSwitch configurationsOverriding hardware iSCSI offload default utilizationUtilizing a vNetwork Distributed SwitchEnabling Jumbo FramesSetting the iSCSI discover address

Appendix B: Installing the MEM with VMware Update Manager