CONTENTS Title Page Copyright Page Preface 1 Introduction to VMS Volume Shadowing 1.1 Overview 1.2 Phase I and Phase II Compatibility 1.3 Distributing Shadow Sets Across VMS Configurations 1.4 Hardware Environment 1.4.1 Processors and Controllers 1.4.2 Compatible Disk Drives and Volumes 1.5 Member Units 1.6 Virtual Units 1.7 Setting Up and Managing Shadowed Systems 2 Setting Up Systems to Use VMS Volume Shadowing 2.1 Licensing VMS Volume Shadowing 2.2 Setting SYSGEN Parameter Values in MODPARAMS.DAT and Running AUTOGEN 2.3 Setting the Volume Shadowing SYSGEN Parameters 2.4 Running the SYSGEN Utility 2.4.1 Displaying SYSGEN Parameters 2.4.2 Changing the Value of SHADOW_MAX_COPY Dynamically 2.5 Booting from a System Disk Shadow Set 2.6 Booting Satellite Nodes from a System Disk Shadow Set 3 Shadow Set Membership 3.1 Creating and Managing Shadow Sets 3.1.1 Naming Formats for Virtual Units and Shadow Set Members 3.1.2 Creating a Shadow Set 3.1.3 Adding Shadow Set Members 3.1.4 Removing Shadow Set Members 3.1.5 Dissolving a Shadow Set 3.2 Maintaining Consistency During Shadow Set Changes 3.3 Copy Operations 3.3.1 Determining the Correct Copy Operation 3.3.2 What Happens if a System Crashes During a Copy Operation? 3.3.3 Examples of Copy Operations 3.4 Displaying Information About a Shadow Set 3.4.1 Listing Shadow Set Virtual Units 3.4.2 Listing Shadow Set Members 3.4.3 Examples of the SHOW DEVICES Command 3.4.4 Using the System Dump Analyzer 3.4.5 Using the F$GETDVI Lexical Function 4 Using the VMS Mount Utility to Perform Shadow Set Operations 4.1 Creating a Shadow Set with the Mount Utility 4.1.1 Mounting a Shadow Set 4.1.2 Examples of Using the Mount Utility 4.1.3 MOUNT Command Qualifiers for Shadowing 4.1.3.1 The /CONFIRM Qualifier 4.1.3.2 The /COPY Qualifier 4.1.3.3 The /INCLUDE Qualifier 4.1.3.4 The /OVERRIDE=SHADOW_MEMBERSHIP Qualifier 4.1.4 MOUNT Command Qualifiers to Avoid for Shadowing 4.1.4.1 The /OVERRIDE=IDENTIFICATION Qualifier 4.1.4.2 The /NOMOUNT_VERIFICATION Qualifier 4.2 Adding Members to a Shadow Set 4.3 Dismounting Members from a Shadow Set 4.4 Dissolving a Shadow Set 4.5 Performing Updates on Individual Shadow Set Members 5 Using System Services to Perform Shadow Set Operations 5.1 Using $MOUNT to Create and Mount Shadow Sets 5.1.1 $MOUNT Shadow Set Item Codes 5.1.2 Constructing the $MOUNT Item List 5.1.3 Examples of $MOUNT Item Lists 5.1.4 Evaluating Condition Values Returned by $DISMOU and $MOUNT 5.2 Using $DISMOU to Dismount Shadow Sets 5.2.1 Removing Member Units from Shadow Sets 5.2.2 Dismounting and Dissolving Shadow Sets 5.2.3 Setting $DISMOU Flags for Shadow Set Operations 5.3 Using $GETDVI to Obtain Information About Shadow Sets 5.3.1 $GETDVI Shadow Set Item Codes 5.3.2 Obtaining the Device Names of All Members of a Shadow Set 5.3.2.1 Starting with the Shadow Set Virtual Unit 5.3.2.2 Starting with a Shadow Set Member Unit 6 Managing Systems with VMS Volume Shadowing 6.1 Upgrading the VMS Operating System on a System Disk Shadow Set 6.2 Migrating from Phase I to Phase II Volume Shadowing 6.2.1 Upgrading from Volume Shadowing Phase I to Phase II 6.2.2 Phase I and Phase II Coexistence on the Same Node or VAXcluster System 6.2.2.1 Naming the Virtual Unit 6.2.2.2 Setting SYSGEN Parameters for Shadowing 6.2.3 Sample User Session 6.3 Performing Backup Operations on a Shadow Set 6.3.1 Using a Shadow Set Copy as a Backup 6.3.2 Using the VMS Backup Utility 6.3.3 Using BACKUP/IMAGE on a Shadow Set 6.3.4 Standalone BACKUP and Volume Shadowing 6.3.4.1 Incompatiblities Between Shadow Sets and Standalone BACKUP 6.3.4.2 Using Standalone BACKUP on Disks That Are Former Shadow Set Members 6.4 Crash Dumping to a Shadowed Disk 7 Configuring Your System for High Data Availability 7.1 Repair and Recovery from Failures 7.2 Shadow Set Configurations 7.3 Performance Information for VMS Volume Shadowing 7.3.1 Performance Effects When a Shadow Set Is in a Steady State 7.3.2 Performance Effects When a Shadow Set Is in a Transient State 7.3.3 Guidelines for Managing Shadow Sets in a System A Messages A.1 Bugcheck Messages That Apply to Shadow Sets A.2 DISMOUNT Message That Applies to Shadow Sets A.3 MOUNT Messages That Apply to Shadow Sets A.4 Mount Verification Messages That Apply to Shadow Sets A.5 OPCOM Message That Applies to Shadow Sets A.6 Shadow Server Messages That Apply to Shadow Sets A.7 SYSINIT Messages That Apply to Shadow Sets A.8 VOLPROC Messages That Apply to Shadow Sets B MOUNT Qualifiers for Volume Shadowing /CONFIRM /COPY /INCLUDE /OVERRIDE /SHADOW C System Services Item Codes for Volume Shadowing Glossary $allocation-class$ . . . failover fault tolerance . . . merge member merge operation . . . storage control block (SCB) system disk . . . volume shadowing EXAMPLES 2-1 Message Display on Nodes Not Registered to Use Volume Shadowing 2-2 Example of a MODPARAMS.DAT file 2-3 Sample Error Messages Indicating SHADOWING Parameter Is Set Incorrectly 2-4 Setting SYSGEN Parameters-A Sample Terminal Session 2-5 DECnet Database Example of a Satellite Node 3-1 Errors That Can Result from Using Zero Allocation Classes 3-2 Full Copy Operation-Creating a New Shadow Set 3-3 Full Copy Operation-Adding a Member to a Shadow Set 3-4 No Copy Operation-Rebuilding a Shadow Set 3-5 Merge Operation-Automatically Rebuilding a Shadow Set with Former Members 4-1 Mounting a Three-Member Shadow Set 4-2 Mounting a Shadowed Volume Set 4-3 Using the /NOASSIST Qualifier 4-4 Checking Shadow Set Member Status with the /CONFIRM Qualifier 4-5 Allowing a Full Copy Operation with the /CONFIRM Qualifier 4-6 Using the /COPY Qualifier to Check Shadow Set Member Status 4-7 Using the /COPY Qualifier to Overwrite Data on Targeted Volumes 4-8 Using the /INCLUDE Qualifier to Restore a Shadow Set 4-9 Using the MOUNT/INCLUDE/CONFIRM Command-Copying Allowed 4-10 Using the MOUNT/INCLUDE/CONFIRM Command-No Copying Allowed 4-11 Adding Shadow Set Members 5-1 Item List to Create and Mount a Shadow Set 5-2 Item List to Create and Mount a Volume Set 5-3 Removing a Member from a Shadow Set 5-4 Dismounting a Shadow Set 5-5 Dismounting and Dissolving a Shadow Set 6-1 Migrating a Phase I Shadow Set to Phase II FIGURES 1-1 Elements of a Shadow Set 1-2 Shadow Sets Accessed Through the VMS MSCP Server 2-1 Distributing a Shadow Set Across Satellite Nodes 7-1 Levels of Availability 7-2 Configuration of a Shadow Set (One VAX-One Controller) 7-3 Configuration of a Shadow Set (One VAX-Two RQDX Controllers) 7-4 Configuration of a Shadow Set (A VAXcluster-Dual Controllers) 7-5 Configuration of a Shadow Set (A High-Availability Local Area VAXcluster) 7-6 Configuration of a Shadow Set (A VAXcluster-With Multiple Star Couplers and Multiple HSC Controllers) TABLES 1 Roadmap to the Organization of This Manual 1-1 Supported Hardware Devices 2-1 Volume Shadowing Parameters 3-1 F$GETDVI Items for Volume Shadowing 4-1 Mount Utility Qualifiers 7-1 Type of Device Failures 7-2 Reasonable Number of Concurrent Copy Threads for Various Systems/Adapters