Load Balancing | Dell MD3200, MD3220 guide

Load Balancing

A load balance policy is used to determine which path is used to process I/O. Multiple options for setting the load balance policies lets you optimize I/O performance when mixed host interfaces are configured.

You can choose one of these load balance policies to optimize I/O performance:

•Round robin with subset—The round robin with subset I/O load balance policy routes I/O requests, in rotation, to each available data path to the RAID controller module that owns the virtual disks. This policy treats all paths to the RAID controller module that owns the virtual disk equally for I/O activity. Paths to the secondary RAID controller module are ignored until ownership changes. The basic assumption for the round-robin policy is that the data paths are equal. With mixed host support, the data paths might have different bandwidths or different data transfer speeds.

•Least queue depth with subset—The least queue depth with subset policy is also known as the least I/Os or least requests policy. This policy routes the next I/O request to a data path that has the least outstanding I/O requests queued. For this policy, an I/O request is simply a command in the queue. The type of command or the number of blocks that are associated with the command are not considered.The least queue depth with subset policy treats large block requests and small block requests equally. The data path selected is one of the paths in the path group of the RAID controller module that owns the virtual disk.

•Least path weight with subset (Windows operating systems only)—The least queue depth with subset policy is also known as the least I/Os or least requests policy. This policy routes the next I/O request to a data path that has the least outstanding I/O requests queued. For this policy, an I/O request is simply a command in the queue. The type of command or the number of blocks that are associated with the command are not considered. The least queue depth with subset policy treats large block requests and small block requests equally. The data path selected is one of the paths in the path group of the RAID controller module that owns the virtual disk.

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Planning: MD3200 Series Storage Array Terms and Concepts

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Dell MD3200, MD3220 owner manual Load Balancing

Contents

Dell PowerVault MD3200 and MD3220 Storage Arrays May Contents Cache Functions and Features Planning MD3200 Series Storage Array Terms and Concepts Virtual Disk Operations Limit Configuring Alert Notifications Out-of-Band and In-Band Management Enabling or Disabling the Event Monitor Managing Host Port Identifiers Configuring Hot Spare Physical Disks Physical Disk Security with Self EncryptingHost-to-Virtual Disk Mapping 122 Creating a Snapshot Virtual Disk UsingSnapshot Using the Simple Path 137 125 Creating a Virtual Disk Copy for an Mscs 145Re-creating a Snapshot Virtual Disk 152 154 160 Using DM Multipathing Devices 168159 161 177 Media Errors and Unreadable Sectors 187Downloading RAID Controller and Nvsram 178 202 Power Supply/Cooling Fan Module 204197 206 Storage Array Support Data 220 Recovering From an Unresponsive Storage 229217 221 Troubleshooting Loss of Communication Safety First-For you and Your ArrayTroubleshooting Storage Array Startup Failure Troubleshooting External Connections 253 Introduction About This Document Dell PowerVault MD3200 Series Storage Array Dell PowerVault Modular Disk Storage Manager Other Information you May Need Introduction Planning About Your Storage Array Overview Hardware Features Front-Panel Features and Indicators Planning About Your Storage Array Item Indicator, Button, or Icon Description Connector Back Panel Features and Indicators Hard-Drive Indicator Patterns Hard Drive Indicators Power Supply and Cooling Fan Features Drive-Status Indicator Pattern Condition Power Indicator Codes Power Indicator Codes Item LED Type Icon Description Planning RAID Controller Modules RAID Controller Modules RAID Controller Module Connectors and Features Function Item Component Function RAID Controller Module-Additional Features Battery Backup UnitComponent Function Shutdown Threshold Type System Password ResetStorage Array Thermal Shutdown Event Description Write-Back Cache Cache Functions and FeaturesCache Mirroring Write-Through Cache Planning MD3200 Series Storage Array Terms and Concepts Physical Disks, Virtual Disks, and Disk Groups Physical Disks Physical Disk States Self-Monitoring Analysis and Reporting Technology Virtual Disks and Disk Groups RAID Levels Virtual Disk StatesRAID Controller Virtual Disk States Description RAID Level Usage RAID RAID Virtual Disk Initialization Segment SizeVirtual Disk Operations Background Initialization Consistency Check Media VerificationCycle Time RAID Level Migration Disk Group OperationsVirtual Disk Operations Limit Segment Size Migration Virtual Disk Capacity Expansion Disk Group Expansion RAID Background Operations Priority Disk Group DefragmentationDisk Group Operations Limit Virtual Disk Migration and Disk Roaming Disk Migration Planning MD3200 Series Storage Array Terms and Concepts Advanced Features Disk Roaming Host Server-to-Virtual Disk Mapping Host TypesSnapshot Virtual Disks Snapshot Repository Virtual Disk Source Virtual Disk Virtual Disk RecoveryVirtual Disk Copy Target Virtual Disk Using Snapshot and Disk Copy Together Multi-Path Software Preferred and Alternate Controllers and Paths Virtual Disk Ownership Load Balancing Monitoring MD3200 Series System Performance Performance Monitor Table Description Column Headings For more information, see the online help topics Planning MD3200 Series Storage Array Terms and Concepts Configuration Overview User Interface Enterprise Management Window Select Inherit system settings for color and font Inheriting the System SettingsSelect Tools→ Inherit System Settings Array Management Window Configuration Overview Configuration About Your Storage Array Out-of-Band and In-Band ManagementOut-of-Band Management Storage Arrays Adding Storage ArraysIn-Band Management Automatic Discovery of Storage Arrays Manual Addition of a Storage ArraySelect Edit→ Add Storage Array Setting Up Your Storage Array Locating Storage Arrays AMW, select Storage Array→ Blink→ Storage Array Naming or Renaming Storage Arrays Name/Rename Storage Arrays dialog appears Setting a Password PasswordType the New password Password Guidelines Viewing Storage Array Connections Select Edit→ Comment Adding/Editing a Comment to an Existing Storage ArrayRemoving Storage Arrays Select Edit→ Remove→ Storage Array Enabling Premium Features Failover Alert Display Changing the Cache Settings on the Storage Array Changing Expansion Enclosure ID NumberChanging the Enclosure Order in the Physical Pane AMW, select Storage Array→ Change→ Enclosure Order Configuring Alert NotificationsSelect Configure Alerts Select All storage arrays Configuring E-mail Alerts Configuration About Your Storage Array Configuring Snmp Alerts Battery Settings Setting the Storage Array RAID Controller Module Clocks Configuration About Your Storage Array Configuration Event Monitor Enabling or Disabling the Event Monitor WindowsLinux Configuration About Your Host Configuring Host Access Using the Mappings Tab Defining a HostSelect Mappings→ Define→ Host Configuration About Your Host Creating a Host Group Removing Host AccessManaging Host Groups Select Mappings→ Remove Removing a Host From a Host Group Moving a Host to a Different Host GroupAdding a Host to a Host Group Select Mappings→ Move Removing a Host Group Host Topology Starting or Stopping the Host Context Agent LinuxWindows Data Path Protection Click Action→ Start Managing Host Port Identifiers Add Host Port Identifier dialog appears Configuration About Your Host Configuration Disk Groups and Virtual Disks Creating Disk Groups and Virtual Disks Creating Disk Groups Introduction Create Disk Group window is displayed Configuration Disk Groups and Virtual Disks Locating a Disk Group Creating Virtual Disks Configuration Disk Groups and Virtual Disks Map later Using Mappings View Changing the Virtual Disk Modification Priority Changing the Virtual Disk Cache Settings 100 Changing the Segment Size of a Virtual Disk 101 Changing the I/O Type Select Virtual Disk→ Change→ Segment Size102 Choosing an Appropriate Physical Disk Type File system typical Database Multimedia Custom103 Physical Disk Security with Self Encrypting Disk 104 105 Creating a Security Key 106 Click Create Key 107 Changing a Security Key Confirm Change Security Key window is displayed108 Saving a Security Key Click Change Key109 Unlocking Secure Physical Disks 110 Configuring Hot Spare Physical Disks Erasing Secure Physical Disks111 Select Physical disk→ Hot Spare Coverage Hot Spare Physical Disk Options window is displayed112 Click Unassign Hot Spares and RebuildGlobal Hot Spares 113 Hot Spare Operation Hot Spare Drive Protection114 Enclosure Loss Protection 115Criteria for Enclosure Loss Protection RAID Level Host-to-Virtual Disk Mapping 116 Creating Host-to-Virtual Disk Mappings 117 Modifying and Removing Host-to-Virtual Disk Mapping 118 Changing Controller Ownership of the Virtual Disk 119 Removing Host-to-Virtual Disk Mapping Select Virtual Disk→ Change→ Ownership/Preferred Path120 Select Disk Group→ Change→ Ownership/Preferred Path 121 Select Disk Group→ Change→ RAID Level Restricted MappingsChanging the RAID Level of a Disk Group 122 123 124 Changing the RAID Level of a Disk Group 125 Storage Partitioning 126 127 Disk Group and Virtual Disk Expansion Select Disk Group→ Add Free Capacity Physical Disks128 Virtual Disk Expansion Using Free CapacityUsing Unconfigured Capacity 129 Exporting a Disk Group Disk Group MigrationExport Disk Group Non-Exportable Components Import Disk Group Importing a Disk Group131 Storage Array Media Scan Non-Importable Components132 Changing Media Scan Settings 133 Suspending the Media Scan 134 Configuration Premium Feature- Snapshot Virtual Disks 135 Creating a Snapshot Virtual Disk Using the Simple Path 136 About the Simple Path 137 138 139 Creating a Snapshot Virtual Disk Using the Advanced Path About the Advanced Path140 141 142 Creating the Snapshot Using the Advanced Path 143 Specify Virtual Disk Parameters window is displayed 144 Specifying Snapshot Virtual Disk Names 145 Snapshot Repository Capacity 146 147 Click Add Physical Disks Add Physical Disks window closes148 Re-creating Snapshot Virtual Disks Select Virtual Disk→ Snapshot→ Re-create149 Disabling a Snapshot Virtual Disk 150 Preparing Host Servers to Re-create a Snapshot Virtual Disk 151 Re-creating a Snapshot Virtual Disk Select Virtual Disk → Snapshot→ Re-create152 Configuration Premium Feature- Virtual Disk Copy 153 Creating a Virtual Disk Copy for an Mscs Shared Disk 154 Virtual Disk Read/Write Permissions Virtual Disk Copy Restrictions155 Creating a Virtual Disk Copy 156 Create Copy Wizard Before you BeginVirtual Disk Copy and Modification Operations 157 Failed Virtual Disk Copy Preferred RAID Controller Module OwnershipFailed RAID Controller Module 158 Copy Manager Copying the Virtual Disk159 Storage Array Performance During Virtual Disk Copy 160 Select Change→ Copy Priority Setting Copy PriorityStopping a Virtual Disk Copy 161 Recopying a Virtual Disk Preparing Host Servers to Recopy a Virtual Disk162 Recopying the Virtual Disk 163 Removing Copy Pairs Select Copy→ Re-Copy164 165 166 Configuration Device Mapper Multipath for Linux 167 Using DM Multipathing Devices Prerequisite Steps168 Device Mapper Configuration Steps Scan for Newly Added Virtual Disks169 170 Create a New fdisk Partition on a Multipath Device Node Add a New Partition to Device Mapper171 Ready for Use Create a File System on a Device Mapper PartitionMount a Device Mapper Partition Important Information About Special Partitions Device Mapper Commands Descriptions 173 Limitations and Known Issues 174 Troubleshooting 175QuestionAnswer 176 Downloading RAID Controller and Nvsram Packages 177 Downloading Both RAID Controller and Nvsram Firmware 178 Click Transfer 179 Downloading Only Nvsram Firmware 180 Select Tools→ Upgrade RAID Controller Module Firmware Upgrade RAID Controller Module Firmware window appears181 182 Downloading Physical Disk Firmware 183 184 Download Environmental EMM Firmware dialog appears AMW, select Advanced→ Maintenance→ Download→ EMM FirmwareDownloading MD1200 Series Expansion Module EMM Firmware 185 Self-Monitoring Analysis and Reporting Technology Smart 186 Media Errors and Unreadable Sectors 187 188 Management Installing Array Components Recommended Tools189 Removing the Front Bezel Installing the Front BezelFront Bezel Optional 190 Removing a Drive Blank Safety Models AMT, E03J, and E04JHard Drives 191 Installing a Drive Blank Removing a Hard Drive192 Removing and Installing a Hard Drive 193 Installing a Hard Drive 194 Removing a Hard Drive From a Hard-Drive Carrier 195 196 Removing a RAID Controller Module Blank Installing a Hard Drive Into a Drive CarrierRAID Controller Module 197 Installing a RAID Controller Module Blank 198 Removing a RAID Controller Module 199 Installing a RAID Controller Module Opening the RAID Controller Module200 Closing the RAID Controller Module 201 RAID Controller Module Backup Battery Unit Removing the RAID Controller Module Backup Battery Unit202 Installing the RAID Controller Module Backup Battery Unit 203 Power Supply/Cooling Fan Module Removing a Power Supply/Cooling Fan Module204 Installing a Power Supply/Cooling Fan Module 205 Control Panel Removing the Control Panel206 207 Installing the Control Panel 208 Backplane Removing the Backplane209 210 16. Removing and Installing the Backplane-PowerVault MD3200 17. Removing and Installing the Backplane-PowerVault MD3220 Installing the Backplane 212 Management Firmware Inventory Viewing the Firmware Inventory213 214 Volume Shadow-Copy Service Microsoft ServicesVirtual Disk Service Management System Interfaces 216 Device Health Conditions Troubleshooting Your Storage Array SoftwareStart-Up Routine 217 On the Setup tab, select Manage a Storage Array 218Status Icon Description 219 Additional Status Icons Description Storage Array Support Data 220 Automatically Collect the Support Bundle Data Enter the Execution summary221 Collecting the Physical Disk Data Event Log222 Recovery Guru 223 Storage Array Profile Select Storage Array→ View→ Profile224 225 Viewing the Logical Associations Viewing the Physical Associations226 Finding Nodes 227 Click Find Next Using Go ToSelect Find all free capacity nodes 228 Recovering From an Unresponsive Storage Array Condition 229 230 231 Locating a Physical Disk 232 Locating an Expansion Enclosure Select Physical Disk→ Blink→ Expansion Enclosure233 Capturing the State Information 234 SMrepassist Utility 235 Recovering From an Unidentified Storage Array Unidentified Devices236 237 238 Starting or Restarting the Host Context Agent Software 239 240 Troubleshooting External Connections Troubleshooting Your ArrayTroubleshooting Loss of Communication 241 Troubleshooting Power Supply/Cooling Fan Module 242 Troubleshooting Array Cooling Problems Troubleshooting Expansion Enclosure Management Modules243 Troubleshooting RAID Controller Modules 244 245 Troubleshooting Hard Drives 246 Troubleshooting Array and Expansion Enclosure Connections 247 Troubleshooting a Wet Storage Array 248 Troubleshooting a Damaged Array Conditions249 Invalid Storage Array ECC ErrorsPCI Errors Critical Conditions Noncritical Conditions 251 252 Visit support.dell.com Getting HelpContacting Dell Click All Support from Support menu 254 Index 255 256 257 258 259 260