Dell PS Series Storage Arrays iSCSI Initiator and Operating System Considerations Optimizing Your SAN Environment for High Availability Dell Storage Engineering January 2017 A Dell EMC Best Practice
Revisions Date Description October 2013 Initial release January 2017 New format, Added XenServer, Windows Server 2012 R2 The information in this publication is provided “as is.” Dell Inc. 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.
Table of contents Revisions.............................................................................................................................................................................2 Preface ................................................................................................................................................................................5 Intended Audience ..........................................................................................................
E Configure your IBM AIX operating system .................................................................................................................20 E.1 F Configure Your Citrix XenServer Operating System ..................................................................................................21 G Technical support and resources ...............................................................................................................................22 G.
Preface Dell™ 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. Dell FS Series appliances, combined with PS Series arrays, offer a high-performance, highavailability, scalable NAS solution.
1 High-Availability Procedure Summary This chapter summarizes the procedures that you must perform to optimize your environment for high availability (HA). 1.1 Proactive Maintenance Support If you have a Dell proactive service agreement, contact your Dell Technical Support representative, who will help you analyze your SAN environment and ensure it is correctly set up for high-availability. 1.
2 About High-Availability iSCSI Data Transfer This chapter describes how to optimize your storage area network (SAN) environment for highly available (HA) iSCSI data transfer. It contains information about how to: Configure Your Hosts for High Availability Configure Your Network for High Availability Note: If you have a Dell proactive service agreement, your Dell Technical Support representative can help you analyze your SAN environment and ensure it is correctly set up for high availability.
3 Configure Your Hosts for High Availability 3.1 Host Integration Tools Dell has automated a portion of this process in the PS Series Host Integration Tools (HIT) kit. The PS Series HIT kits provide integrated software such as MPIO modules, enhanced data protection, automated provisioning, and alerts for Windows, VMware, and Linux hosts. If installed, this software implements changes (such as configuration options on the hosts) that follow Dell's recommended best practices.
4 Configure Your Network for High Availability A PS Series iSCSI SAN can be operated in any network that supports the industry standards and IP subnet design guidelines described in this chapter. Because of this flexibility, many network design and configuration choices can affect SAN performance. For more network design and configuration information to support the use of a PS Series SAN, see the Dell PS Series Configuration Guide, which can be downloaded from: http://en.community.dell.
All switches in the SAN must have jumbo frames enabled. This requirement applies to SANs connected to either a PS Series array or an FS Series appliance.
Both LAG or Stacking interconnects can be used as the bridging mechanism between redundant switches in the PS Series SAN, but each method has a different set of considerations that might make one approach more preferable than the other. For more information about LAG and Stacking considerations, see the Dell PS Series Configuration Guide at: en.community.dell.cornltechcenter/storage/w/wiki/2639.equallogic-configurationguide.
A Configure Your Microsoft Windows Operating System The following sections describe how to configure settings on your Microsoft® Windows servers to ensure high availability. A.1 Procedure Summary To ensure high availability, configure the settings on your Microsoft® Windows servers as follows. If you have installed the HIT kit, skip step 3. 1. 2. 3. 4. A.1.1 Install the recommended Microsoft hotfixes. Install the HIT kit and proceed to step 4.
HIT/Microsoft toolkit. A path failover occurs between storage controllers. In this scenario, the system loses track of one or more logical unit numbers (LUNs). Therefore, not all the LUNs appear in the Device Manager. Additionally, the system no longer sends out I/O requests to the missing LUNs. Note: To resolve this issue in Windows Server 2012, install update rollup 2889784 Recommendation: Microsoft has released 2851144 hotfix to address this issue.
To fix this problem, apply the hotfix specified in Microsoft Knowledge Base article 979711, support.microsoft.com/kb/979711, to each cluster node. Performance Degradation When Heavy Disk I/O Load The performance of a computer that is running Windows Server 2008 R2 or Windows 7 decreases by 20 percent under a heavy disk I/O load. Apply the hotfix specified in Microsoft Knowledge Base article 982383, support.microsoft.com/kb/982383.
B Install the Multi-extension module for VMware operating system VMWare vSphere provides the Pluggable Storage Architecture (PSA), which enables multipath configuration for high availability and increased performance. The modular design of the architecture accepts third-party multipathing plugins that enable enhanced functionality specific to storage device models.
C Configure your Linux operating system If you do not have the HIT kit installed, the following sections describe the configuration settings you need to apply on your Linux hosts to ensure high availability. See Table 1 for a summary of the recommended settings. C.1 Configure SCSI Device Settings Using the udev Facility The Linux udev utility can be used to dynamically modify device settings every time a new device is added or changed.
arrays and the Linux host. Dell recommends that you change the setting to manual. The HIT/Linux eqltune utility recommends this change, but does not automatically implement it: node.startup = manual C.3 Configure Linux Networking Dell's best practice recommendation is to configure multipathing for Ethernet interfaces on a Linux host to connect to a PS Series group.
Loosen IPv4 Reverse Path Filtering To allow multiple iSCSI connections in a multiple NIC per subnet configuration, reverse path filtering must be loosened. Use this setting: net.ipv4.conf.ethX.rp_filter=2 Summary of Recommended Changes Area Setting Default Value Recommended Value1 (PS Series) SCSI block devices Device timeout 30 seconds 60 seconds Per SCSI device read-ahead buffer 128KB 1024KB Per SCSI device I/O scheduler CFQ noop iSCSI settings node.session.iscsi.
D Configure your Oracle Solaris 10 operating system You can use the default initiator configuration for Oracle® Solaris® 10 operating systems. No changes are required. However, you might experience the following issue. D.1 Zero-Length Volumes By default, the Solaris 10 initiator automatically connects to all volumes it discovers. If it connects to a zerolength volume (such as the vss-control volume), it panics.
E Configure your IBM AIX operating system The AIX native iSCSI controller does not perform device discovery, so you will need to know your iSCSI IQN target names specifically. In addition IBM® AIX® systems might experience the following issue. E.1 iSCSI Initiators Lose Volume Connectivity In some cases, after a load-balancing operation completes, AIX iSCSI initiators lose volume connectivity. This issue can be corrected by applying a patch to your AIX system.
F Configure Your Citrix XenServer Operating System You may use the Citrix XenServer Open-iSCSI multipathing software initiator to provide native MPIO support and discovery. More information is available on TechCenter (login required): http://en.community.dell.com/techcenter/extras/m/white_papers/20442325.
G Technical support and resources Dell.com/support is focused on meeting customer needs with proven services and support. Dell TechCenter is an online technical community where IT professionals have access to numerous resources for Dell EMC software, hardware and services. Storage Solutions Technical Documents on Dell TechCenter provide expertise that helps to ensure customer success on Dell EMC Storage platforms. G.
