unisys ClearPath Enterprise Servers Remote Database Backup Planning and Operations Guide ClearPath MCP 14.0 April 2012 8600 2052 309
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Contents Section 1. Overview of the Remote Database Backup System Documentation Updates... 1 2 What s New?... 1 3 What Remote Database Backup Can Do for You... 1 4 Roles of Databases and Hosts in a Remote Database Backup System... 1 5 Configurations of Remote Database Backup Systems... 1 7 Basic Remote Database Backup Hardware and Software Requirements... 1 12 Audit Trail Synchronization... 1 14 The Next Step More About Audit Transmission Modes... 1 19 Section 2. Understanding Audit Transmission Modes Audit Block (ABW) Transmission Mode... 2 2 Error-Handling Options for the ABW Mode... 2 4 Drop Error-Handling Option... 2 6 Operator Error-Handling Option... 2 7 Audit File Mirror (AFM) Transmission Mode... 2 8 Audit Transmission Modes (AFS, SCA, and NSC)... 2 10 Audit File Switch (AFS) Mode... 2 11 Server Capable (SCA) Mode... 2 13 Not Server Capable (NSC) Mode... 2 14 Audit Transmission Mode Options... 2 15 Impact of the Block Transmission Mode on Resources... 2 17 Impact of the File Transmission Modes on Resources... 2 19 Impact of the AFS Mode on Resources... 2 20 Impact of the SCA and NSC Modes on Resources... 2 22 The Next Step Selecting Options and System Resources for Your Goals... 2 24 Section 3. Selecting Remote Database Backup Options and System Resources for Your Goals Overview of the Process... 3 2 Identifying Your Goals for Remote Database Backup... 3 3 Clarifying Your Disaster Recovery Goals... 3 4 Considerations About the Use of the Primary Host... 3 6 Establishing Performance Requirements... 3 7 Selecting Audit Transmission Modes to Meet Your Goals... 3 8 Describing Your Resources... 3 10 Introduction to Gathering Data to Calculate Utilization... 3 12 8600 2052 309 iii
Contents A Two-Step Process... 3 14 General Impact of Remote Database Backup on Existing Resource Utilization... 3 15 Gathering Data on Existing Network Utilization... 3 17 Gathering Data on Future Network Utilization with Remote Database Backup... 3 18 Preliminary Measurements for the ABW Mode... 3 19 Preliminary Measurements for the AFS, SCA, and NSC Modes... 3 21 Obtaining Communications Processor Utilization Statistics... 3 24 Gathering Data on Host Processor Utilization... 3 26 Calculating the Total Secondary Host Processor Utilization... 3 28 The Next Step Preparing to Configure a Remote Database Backup System... 3 30 Section 4. Preparing to Configure a Remote Database Backup System Overview of Preparation Tasks... 4 2 Checking on the Remote Database Backup Installation... 4 3 Preparations for Using a Nonusercoded Database... 4 5 Understanding Remote Database Backup Software... 4 9 Understanding Other Remote Database Backup Software... 4 14 Automating Some Remote Database Backup Operations... 4 18 Understanding How Remote Database Backup Uses Port Files... 4 19 Understanding More About the ABW Mode... 4 21 Automatic Audit Synchronization Process of the ABW Mode... 4 25 Integrating Remote Database Backup into Your Security Setup... 4 27 Setting Up Guard Files for the Secondary Host... 4 28 Preparing Personnel to Run the Remote Database Backup System... 4 30 Reviewing DASDL Source Files... 4 31 Designating Usercodes and Packs... 4 34 Ensuring Database File Availability on the Secondary Host... 4 38 I/O Timeout Value for the Ports... 4 40 Responding to a Port-I/O Timeout Error... 4 41 Influencing Tracker Performance... 4 42 Affecting the Speed of Tracker Performance... 4 42 Manipulating the Frequency of Restart Points... 4 44 Section 5. Configuring a Remote Database Backup System Configuration Tasks... 5 2 Defining Your Remote Database Backup System... 5 3 Initializing and Defining the Primary and Secondary Hosts... 5 3 Enabling the Remote Database Backup System... 5 5 iv 8600 2052 309
Contents Cloning the Database on the Secondary Host... 5 6 Making the Required Database Files Available on the Secondary Host... 5 7 Specifying Dump Information and Pack Names for Database Structures on the Secondary Host... 5 10 Identifying Pack Names for Database Software Files on the Secondary Host... 5 12 Specifying Pack Names for Database Guard Files on the Secondary Host... 5 14 Providing the Titles of the DMCONTROL and DMUTILITY Code Files on the Secondary Host... 5 15 Selecting a Method of Running the Clone Operation... 5 15 Verifying the Remote Database Backup System... 5 19 Starting the Secondary Database After a Clone Operation... 5 21 Synchronizing the Databases After Cloning with an Online Dump... 5 21 Section 6. Performing Takeovers Overview of a Takeover... 6 2 Performing Takeover Tasks... 6 4 Terminating Update Programs... 6 4 Transferring and Applying Audit Images... 6 4 Estimating Lost Transactions... 6 5 Establishing the New Primary Host... 6 7 Establishing the New Secondary Host... 6 11 Managing the Transaction Server Synchronized Recovery... 6 14 Section 7. Monitoring Your Remote Database Backup System Overview of Remote Database Backup Monitoring... 7 2 Accessing Messages... 7 4 Accessing the Current State of Audit Transfers... 7 5 Accessing Cumulative Remote Database Backup Statistics... 7 10 Interpreting Remote Database Backup Statistics... 7 14 Accessing Database Statistics on Remote Database Backup Performance... 7 16 Section 8. Managing a Remote Database Backup Environment Interdependencies in the Remote Database Backup Environment... 8 2 Audit File Accumulation... 8 3 Acknowledgment of Audit Files... 8 4 Viewing and Updating Host Information Records... 8 7 Viewing a Host Information Record... 8 9 Modifying a Host Information Record... 8 10 Deleting the Host Information Record for the Secondary Host... 8 12 8600 2052 309 v
Contents Changing the Audit File Transmission Mode... 8 13 Cloning the Database on the Secondary Host... 8 15 Disabling Tracker... 8 19 Performing an Offline Dump of the Secondary Database... 8 24 Performing Replication of the Secondary Database... 8 27 Disabling the Remote Database Backup System... 8 29 Reenabling the Remote Database Backup System... 8 31 Using Visible DBS Commands in the Remote Database Backup Environment... 8 32 Section 9. Updating and Reorganizing an Enterprise Database Server Database in the Remote Database Backup Environment DASDL Updates in the Remote Database Backup Environment... 9 2 Processing Updates Under the ABW or AFM Mode... 9 4 Processing Updates Under the AFS, SCA, or NSC Mode... 9 5 Changing Code File or Guard File Names and Pack Locations... 9 7 Adding New Structures... 9 8 Tracker and the Reinitialization of an Existing Structure... 9 11 Reorganizations in the Remote Database Backup Environment... 9 12 Minimizing the Consequences of an Aborted Reorganization... 9 13 Deciding Whether to Perform Tasks Manually or Automatically... 9 14 Effects of Reorganization Open Options... 9 15 Availability of Database Structures During a Reorganization... 9 16 Handling Nonusercoded and Usercoded Databases... 9 16 Auditing During Reorganizations... 9 18 Performing a Structure Clone Operation... 9 26 Handling the Effects of an Extensive Online Reorganization... 9 30 Section 10. Recovering a Database in the Remote Database Backup Environment Types of Recovery in the Remote Database Backup Environment... 10 2 Rebuild Recovery... 10 3 Rollback Recovery... 10 4 Halt/Load and Abort Recovery... 10 5 Reconstruct Recovery... 10 7 Copying Database Structures from an Offline Dump... 10 10 Restoring Lost or Corrupt Database Files... 10 11 vi 8600 2052 309
Contents Section 11. Using an Enterprise Application Environment in a Remote Database Backup Environment Finding the Information You Need... 11 2 Secondary Database Functions... 11 4 Hints for Successful Enterprise Application Environment Operations... 11 5 Section 12. Troubleshooting Minimizing Problems... 12 2 Resolving Operational Problems with Database Operations Center... 12 3 Enable Operation... 12 3 Clone Operation... 12 5 Mode Change... 12 10 Resolving Takeover Problems... 12 11 Resolving Primary Database Problems... 12 14 Resolving Secondary Database Problems... 12 18 Reestablishing Synchronization... 12 26 Resolving Catchup Problems... 12 26 Resolving Tracker Problems... 12 28 Resolving Miscellaneous Problems... 12 31 Resolving Port-I/O Timeout Errors... 12 32 Resolving Updating and Reorganization Problems... 12 37 Resolving Tape Audit Failures... 12 40 Section 13. Programmatic Interfaces Establishing the Link to the RDB Support Library... 13 2 Using the Takeover Entry Point... 13 3 Example Takeover Entry Point ALGOL Program... 13 11 Using the RDB_INFO Entry Point... 13 15 Using the GET_PRIMARY_MODE Entry Point... 13 20 Example GET_PRIMARY_MODE Application Program Text... 13 20 Using the SET_RDB_MODE Entry Point... 13 22 Using the GET_RDB_MESSAGE Entry Point... 13 28 Section 14. SYSTEM/RDBOPS Running RDBOPS... 14 1 Appendix A. Sample Clone WFL Job Sample Full Clone WFL Job... A 2 8600 2052 309 vii
Contents Appendix B. Resource Assessment Forms System Resource Description Form... B 2 Database Description Form... B 3 Primary Host Database Applications List Form... B 4 Primary Host Nondatabase Applications List Form... B 5 Secondary Host Applications List Form... B 6 Network Description Form... B 7 Audit Generation Rate Form... B 8 Applications Activity Form... B 9 Appendix C. Methods of Measuring Resource Utilization Tools to Measure Database Activity... C 2 Tools to Obtain an Audit Generation Rate... C 7 Tools to Obtain an Audit Block Size... C 9 Appendix D. Operational Considerations for Mirrored Audit Remote Database Backup System Environment... D 2 Setting Up Shared Disks on ClearPath Hosts for EMC Mirrored Disks... D 4 Recovering from a Corrupted Pack Label on Target Packs... D 6 Changing Audit File Transmission Modes... D 6 Disabling the Remote Database Backup System... D 8 Performing a Planned Takeover in AFM Mode... D 9 Restoring the Original Remote Database Backup Configuration Following a Planned Takeover... D 10 Performing an Unplanned Takeover in AFM Mode... D 13 Restoring the Original Remote Database Backup Configuration Following an Unplanned Takeover... D 14 Index... 1 viii 8600 2052 309
Figures 4 1. How Remote Database Backup Components Work Together for the ABW Mode... 4 13 4 2. Normal Flow of Audit Blocks in ABW Mode... 4 21 4 3. Catchup Process Flow of Audit Blocks in ABW Mode... 4 24 4 4. Sample Output from the Visible DBS STATUS Command... 4 43 4 5. Relation of Restart Points to Control Points... 4 45 7 1. Sample Report from the AUDIT ANALYZE AFN Command... 7 16 7 2. Sample Report Including AUDIT PROCESSOR TIMES Command Information... 7 17 8 1. Sample Output from the LIBS Command... 8 21 14 1. Sample image of the TEMPLATE/RDB/CONFIG file... 14 6 C 1. Sample Output from the AUDIT ANALYZE AFN Command (Part 1)... C 4 C 1. Sample Output from the AUDIT ANALYZE AFN Command (Part 2)... C 5 D 1. Remote Database Backup System Environment and How It Works with Disk Subsystems... D 3 8600 2052 309 ix
Figures x 8600 2052 309
Tables 1 1. Audit Transmission Modes... 1 16 9 1. Effects of the Open Options on Database Availability... 9 15 8600 2052 309 xi
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Section 1 Overview of the Remote Database Backup System Purpose Audience Prerequisites Conventions This guide provides the information necessary to understand the Remote Database Backup capability. The primary audience for this guide is the database personnel responsible for administrative and supervisory day-to-day database operations. System administrators and computer operators are a secondary audience. Anyone using this guide should be familiar with basic Enterprise Database Server concepts. You should have extensive experience in using Enterprise Database Server utilities. Lastly, you should have experience with creating and updating an Enterprise Database Server database. References to additional information contained in other books or sections of this guide are listed at the end of each subsection under the heading Related Information Topics. All screens referred to in this document are part of Database Operations Center. This document uses the following abbreviations: Kbps (kilobits per second) KBps (kilobytes per second) Mbps (megabits per second) MBps (megabytes per second) 8600 2052 309 1 1
Documentation Updates Remote Database Backup Overview This section contains overview information about the Remote Database Backup system, including What Remote Database Backup can do for you Roles of databases and hosts in a Remote Database Backup system Configurations of Remote Database Backup systems Basic Remote Database Backup hardware and software requirements Audit trail synchronization Documentation Updates This document contains all the information that was available at the time of publication. Changes identified after release of this document are included in problem list entry (PLE) 18824001. To obtain a copy of the PLE, contact your Unisys representative or access the current PLE from the Unisys Product Support Web site: http://www.support.unisys.com/all/ple/18824001 Note: If you are not logged into the Product Support site, you will be asked to do so. 1 2 8600 2052 309
What s New? What s New? This guide provides changes and information specific to the current release as shown in the following table: Section 2 Section 3 Section 8 Section 12 Section 13 Section 14 Location New Or Revised Information Updated text for ABW and AFM Transmission Mode References to Network Control Facility (NCF) removed Note added to Full Clone Tasks subheading to address NSC New topic added: STRUCTURECLONE Required Following Successful STRUCTURECLONE Update to Catchup Does Not Run After Mode Change from SCA to ABW subsection to include NSC Update to GET_RDB_MESSAGE Application Program Text example New RDBOPS section added 8600 2052 309 1 3
What Remote Database Backup Can Do for You What Remote Database Backup Can Do for You What Is Remote Database Backup? Remote Database Backup is a database recovery system. Remote Database Backup can be a key component of any disaster recovery plan because it minimizes the amount of time needed to recover from a loss of database access. Remote Database Backup also minimizes loss of productivity, loss of revenue, and loss of business because of interruptions in the ability to access your database. Remote Database Backup works with Enterprise Database Server databases. Components of a Remote Database Backup System The Remote Database Backup system consists of a database and a copy of the database. One database is update capable and the other can be used for inquiry purposes only. The update-capable database is called the primary database. The host on which this database resides is called the primary host. The current online remote database copy, called the secondary database, is inquiry capable only. The host on which this database resides is called the secondary host. The configuration of the primary and secondary databases on their separate hosts is called a Remote Database Backup system. A single host can participate in multiple Remote Database Backup systems. What Remote Database Backup Does Remote Database Backup enables you to maintain a current online inquiry-only copy of a database on an enterprise server separate from the enterprise server on which the update-capable database resides. The host locations can be at the same site or at two geographically distant sites. Remote Database Backup keeps the database copy up-to-date by applying the audit images from the audited database to the database copy. A choice of four audit transmission modes enables you to choose the means of audit transfer between hosts that best suits your needs. If the primary database or primary host fails, you can quickly switch the primary database operations to the secondary database on the secondary host. Related Information Topics For information about... Refer to... Audit transmission modes Sections 2, 3, and 4 Resource assessment for using Remote Database Backup Section 3 1 4 8600 2052 309
Roles of Databases and Hosts in a Remote Database Backup System Roles of Databases and Hosts in a Remote Database Backup System Roles of the Databases In the Remote Database Backup system, the terms primary and secondary indicate the intended function of each copy of the database and the host on which it resides. The following table shows the functions of the primary and secondary databases. Database Primary Secondary Function Database inquiry and update Database inquiry only The secondary database Cannot be updated by application programs The secondary database is modified only by the application of audit images of transactions performed on the primary database. Can assume the role of the primary database if the primary database becomes unavailable Roles of the Hosts One complete Remote Database Backup system is made up of one database the primary database on one host, and one copy of that database the secondary database on another host. A host is the system on which a primary or secondary database resides. A host can function as a primary host in one Remote Database Backup system and concurrently function as a secondary host for another Remote Database Backup system. In addition, one host can function as a secondary host (or primary host) for multiple Remote Database Backup systems. When you first initialize Remote Database Backup for a database, by default, the primary host is the host upon which the database resides. The other host you define for that database is designated as the secondary host. It remains a secondary host until a takeover is performed or until the Remote Database Backup capability is disabled. The primary and secondary hosts must have sufficient resources to support your Remote Database Backup system and your application environment. 8600 2052 309 1 5
Roles of Databases and Hosts in a Remote Database Backup System A Scenario of How the Databases Work Together The following scenario demonstrates how the primary database on a system called Host1 and the secondary database on a system called Host2 work together in response to, or possibly in anticipation of, an interruption on the primary host. In this scenario, the application normally runs against the primary database, with Remote Database Backup transferring audit images to the secondary database. Inquiry programs can be running against the secondary database. Then in response to, or possibly in anticipation of, an interruption on the primary database, you decide that the secondary database should assume responsibility for transaction processing. A designated person at your site, such as a database administrator (DBA), issues a command to tell the secondary database to take over the role of the primary database. Before the takeover command is issued, the primary database, if it is still available, should be brought down. After the takeover command is issued, the DBA transfers all update processing to Host2. When the takeover process completes, Host2 becomes the primary database for all transaction processing. If Host1 is still available, the DBA at the site has the option of running inquiry programs against the copy of the database on Host1. As you can see, the roles of the two databases are reversed and audit images are now transferred from Host2 to Host1. 1 6 8600 2052 309
Configurations of Remote Database Backup Systems Configurations of Remote Database Backup Systems Introduction You can configure the hosts and databases within the Remote Database Backup environment in many different ways. The choices range from the simple to the complex: A simple configuration would be one Remote Database Backup system two hosts with one database on each host. A complex configuration could involve multiple Remote Database Backup systems many hosts and databases configured on several hosts. Although there are many possible configurations, the most typical configurations are described in the following text. One Remote Database Backup System The following figure illustrates a single primary database and a single secondary database configuration. The primary payroll database on one host is backed up by a secondary payroll database on the other host. 8600 2052 309 1 7
Configurations of Remote Database Backup Systems Reciprocal Backup Hosts for Two Remote Database Backup Systems The following figure illustrates the configuration of two Remote Database Backup systems in which each host acts as a reciprocal backup host for the other. Both hosts support a primary database and a secondary database. 1 8 8600 2052 309
Configurations of Remote Database Backup Systems Multiple Primary Hosts with a Single Backup Host The following figure illustrates a configuration with multiple primary hosts and a single backup host. One host contains all the secondary databases for primary databases on several other hosts. This configuration illustrates a centralized corporate and division strategy in which three division hosts each contain a primary database that is backed up on the corporate host. The corporate host allows you to inquire against each of the secondary databases. Each primary database on a division host is both inquiry and update capable. 8600 2052 309 1 9
Configurations of Remote Database Backup Systems Multiple Remote Database Backup Systems with Multiple Backup Hosts The following figure illustrates a configuration with multiple databases on one corporate host and multiple backup databases on several other hosts. The corporate host contains multiple primary databases that are backed up by secondary databases on other hosts. This configuration illustrates three primary databases running on the corporate host. This host allows inquiry against and update to each primary database payroll, accounting, and billing. Each of these databases is backed up by a secondary database on one division host. Each secondary database on a division host allows only inquiry users. 1 10 8600 2052 309
Configurations of Remote Database Backup Systems Two Remote Database Backup Systems Sharing Primary and Secondary Hosts The following figure illustrates the configuration of two Remote Database Backup systems that share a common primary host and secondary host. The primary payroll and accounting databases on one host are backed up by secondary payroll and accounting databases on another host. The host containing the primary databases can be used for both update and inquiry purposes, while the host containing the secondary databases can be used for inquiry purposes only. 8600 2052 309 1 11
Basic Remote Database Backup Hardware and Software Requirements Basic Remote Database Backup Hardware and Software Requirements The following table lists the basic hardware and software requirements for the Remote Database Backup system. For additional details on any item of hardware or software, contact your account manager. Hardware/Software Hardware Memory MCP/AS Remote Database Backup product Enterprise Database Server data management software Network Disk Requirement Two enterprise servers. The two systems do not need to be the same model, but extremes should be avoided, for example, pairing servers of widely varying available performance and capacity. Refer to the Enterprise Database Server Getting Started and Installation Guide. The primary and secondary hosts can run on different software release levels. The same software release level must be installed on both the primary and secondary hosts. The same software release level must be installed on both the primary and secondary hosts. Hardware and software sufficient to handle Remote Database Backup traffic and other traffic between the primary and secondary hosts and BNA services. If audit files will be transferred manually only under NSC mode, a network is not required. Enough storage capacity on both hosts to accommodate system software, application software, and your database and audit files. Audited Database Requirement Because Remote Database Backup uses the audit images from the primary database to update the secondary database, any database that is a candidate for Remote Database Backup must be audited. You can use single or duplicate audit files. Compatible Databases Remote Database Backup works with any database that uses the Enterprise Database Server for physical file management. 1 12 8600 2052 309
Basic Remote Database Backup Hardware and Software Requirements Incompatible Databases Remote Database Backup is not qualified and not supported to work with the Transaction Processing System (TPS). Remote Database Backup also does not work with flat files, for example, KEYEDIO or KEYEDIOII files. Open Distributed Transaction Processing and Remote Database Backup You can use Remote Database Backup with databases that participate in Open Distributed Transaction Processing operations. However, in the event of a takeover, the synchronization between all databases in the Open Distributed Transaction Processing global transaction cannot be guaranteed. Related Information Topics For information about... Refer to... Compatible MCP release levels Configuring a Remote Database Backup system Open Distributed Transaction Processing and Remote Database Backup ClearPath MCP Migration Guide Section 5 Section 4 8600 2052 309 1 13
Audit Trail Synchronization Audit Trail Synchronization Importance You need to decide on the level of audit trail synchronization you want for your Remote Database Backup system. This means answering the question, How closely must the backup database match its source? Or, in Remote Database Backup terms, How closely synchronized should the secondary database audit trail be to the primary database audit trail? Your answer to these questions impacts the Remote Database Backup configuration options you choose and therefore the resources you need to meet your requirements. Modes of Audit Transmission Remote Database Backup provides five specific audit transmission modes that enable you to regulate Whether the transmission of audit images is automatic or manual Whether the transmission of audit images is as individual audit blocks or whole audit files Whether the transmission of audit images can be interrupted (that is, suspended) The degree of audit trail synchronization between the primary and secondary hosts Audit Block Write (ABW) The secondary audit trail is constantly and automatically kept synchronized with the primary database audit trail on a block-by-block basis. The ABW mode enables this close synchronization level by Handling interruptions to audit transmissions through one of two error-handling options Initiating a catch-up process for audit block transfer whenever the usual synchronization level is disrupted When the system detects a need for a Catchup process, you can specify the time synchronization restart interval on the Host screen before the Catchup process begins. Audit File Mirror (AFM) The secondary audit trail is constantly and automatically kept synchronized with the primary database audit trail on a block-by-block basis. The AFM mode enables this close synchronization level by supporting the remote mirrored disk environment and the shared disk feature. The physical mirroring of the audit disk is external to a Remote Database Backup system. At the secondary host, the RDB-agent task monitors audit activity occurring at the primary host. This monitoring cycle also includes re-initiation of Tracker if it is not 1 14 8600 2052 309
Audit Trail Synchronization running. As long as the RDBSUPPORT library is active, the RDB-agent task re-initiates Tracker and attempts to monitor audit activity. This monitoring cycle occurs at 20 second intervals unless communication has been disrupted, in which case the interval is increased to 60 seconds. When communication is resumed, the interval is returned to 20 seconds. If the audit transfer mode from the secondary host to he primary host is NSC mode, then the audit monitoring activity at the secondary host cannot be accomplished. Refer to the System Administration Guide and the System Commands Reference Manual for additional information about the shared disk feature. Audit File Switch (AFS), Server Capable (SCA), and Not Server Capable (NSC) The secondary database audit trail can be kept periodically synchronized with the primary database audit trail through Automatic update, audit file by audit file Remote Database Backup enables this synchronization level with the audit file switch (AFS) audit transmission mode. Compatible file transfer products are Native File Transfer (NFT) and FTRapid. If a transmission does not complete, Remote Database Backup automatically retries it at the next audit file switch. Operator-initiated update through a manual transfer of audit files Remote Database Backup allows the operator to choose a level of audit trail synchronization with the following audit transmission modes: Server capable (SCA) mode that can employ either the network or tape to transfer audits Not server capable (NSC) mode that can also employ either the network or tape to transfer audits, but does not perform any Remote Database Backup network-related services such as reporting information from the remote host on the View Remote Auditing Status screen or automatically copying files during the enable operation In the manual method, you transfer all audit images as individual audit files by using whatever means available. For example, you could transfer the files through a physical tape or a network. Remote Database Backup has no knowledge of or control over the transfer of the audit files, and you must inform Remote Database Backup of the presence of the audit files on the secondary host. Table 1 1 briefly describes the five Remote Database Backup audit transmission modes and identifies the degree of audit trail synchronization that you can expect with each mode. 8600 2052 309 1 15