Data Replication - How To

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Start/Suspend/Resume/Abort Data Replication Activity

Monitor Data Replication Activities

Configure Orphan File Processing

View Orphan Files

Specify CDR Log File Location on Source and Destination Computers (CDR on Windows only)

Specify the CDR Log File Update Interval

Configure Throttling for CDR Replication Activities

Specify a Snap

Perform Replication Prediction

Using ContinuousDataReplicator in a Fan-In Configuration

Perform Initial Transfer of Data Without Using Baselining Phases

Replicate the Destination Data Back to the Source Computer

Start/Suspend/Resume/Abort Data Replication Activity

Related Topics:

Before You Begin

Required Capability: Capabilities and Permitted Actions

To change the state of a Replication Pair:

Select one of the following methods:

 

To suspend all data replication activity for a Replication Set:

  1. In the CommCell Browser, right-click a Replication Set in the source machine, and select All Tasks, then select Suspend Data Transfer.
  2. Data replication activities are suspended for all Replication Pairs in the Replication Set.
note.gif (292 bytes) To restart data replication activities, use the procedures above to start activity for one or more Replication Pair(s).

Monitor Data Replication Activities

The Data Replication Monitor only displays data replication activities for Replication Sets. All activity other than data replication activities, such as Recovery Point creation, is reflected in the Job Controller.

Monitor data replication activities

View details of data replication activities

View the failed files for a Replication Pair

Filter which clients' activities are displayed

Required Capability: Capabilities and Permitted Actions

To monitor data replication activities:

  1. In the CommCell Browser, right-click the CDR icon, and select All Tasks, then select Data Replication Monitor.
  2. In the Data Replication Monitor, all replication activities will be displayed for each Replication Pair. For more information about the States displayed, see Monitoring Data Replication.

 

To view details of data replication activities for a Replication Pair:

  1. In the Data Replication Monitor, right-click any Replication Pair, and select Details.
  2. The Pair Activity will be displayed with additional details about the job.

 

To view the failed files for a Replication Pair:

  1. In the Data Replication Monitor, right-click any Replication Pair, and select View Failed Files.
  2. If any failed files have been logged for this Replication Pair, they will be displayed.

 

To filter which clients' activities are displayed:

  1. In the Data Replication Monitor, right-click any Replication Pair, and select Filters.
  2. In the Filter Operations dialog box, select from the following:
  3. Click Apply and then click Close.
  4. The Data Replication Monitor will now show activities only for the Replication Pairs for the clients defined in your selected filter.

Configure Orphan File Processing

Before You Begin

Required Capability: Capabilities and Permitted Actions

To configure orphan file processing for a Replication Set:

  1. From the CommCell Browser, right-click the Replication Set on a source computer, and select Properties.
  2. From the Replication Set Properties (Orphan Files) tab, perform the following selections:
  3. Click OK.

View Orphan Files

Related Topics:

Required Capability: Capabilities and Permitted Actions

To view the orphan files for a Replication Pair:

  1. In the CommCell Browser, right-click the ContinuousDataReplicator icon on a source computer, and from All Tasks, select Data Replication Monitor.
  2. In the Data Replication Monitor, right-click a Replication Pair and select View Orphan Files.

Specify CDR Log File Location on Source and Destination Computers

Before You Begin

Required Capability: Capabilities and Permitted Actions

To specify a location for the CDR log files:

  1. In the CommCell Browser, right-click the Client on either a source or destination computer, and select Properties.
  2. In the Advanced tab of the Client Computer Properties screen, type or browse to path for CDR Log File Location.
  3. Click OK to save your changes.

Specify the CDR Log File Update Interval

For CDR on Windows, you can specify the time interval at which Replication Logs are transferred if there has not been sufficient change activity to fill the log and cause automatic transfer. This time interval is set to 15 minutes by default. For more information, see Data Replication - Replication Logs.

For CDR on UNIX, this setting is not used, as the logs are sent to the destination and replayed in real time.

Before You Begin

Required Capability: Capabilities and Permitted Actions

To specify the update interval for CDR log files:

  1. In the CommCell Console, click the Control Panel icon, then double-click Job Management.
  2. In the Job Updates tab of the Job Management dialog box, specify the number of minutes in the State update interval for ContinuousDataReplicator field.
  3. Click OK to save your changes.

Configure Throttling for CDR Replication Activities

Related Topics:

Required Capability: Capabilities and Permitted Actions

To configure throttling for CDR replication activities:

  1. In the CommCell Browser, right-click the ContinuousDataReplicator icon of the source machine, and select Properties.
  2. In the Operational Parameters tab of the CDR Properties screen, specify any of the following:

    Destination Computer: (CDR on Windows only)

    Source Computer:

  3. Click OK to save your changes.

Specify a Snap Engine

Before You Begin

Required Capability: Capabilities and Permitted Actions

To specify a snap engine on Windows to the destination computer:

  1. In the CommCell Browser, right-click the Replication Set on the source computer and select Properties.
  2. In the Replication Options tab, select one of the choices in the Select Snap Engine Type for Recovery Point Creation section.
  3. Click OK to save your changes.

    On UNIX, CDR software automatically recognizes the File Systems configured on the destination computer and detects the appropriate snap engine. For more information on supported snap engines, see Snapshot Engines - Support.

Perform Replication Prediction

Each listed command should be run from a command line prompt, in the folder where the base package resides.

Related Topics:

Required Capability: Capabilities and Permitted Actions

 

Start monitoring

All active Replication Pairs are automatically monitored from the time they are configured. To monitor an object not configured using CDR, you will need to add the path of the object to the list of monitored objects by executing this command.

Windows: predict -folder <full path and folder name>

Examples:

UNIX: cdrp -start <fname>

 

View data for a monitored volume, folder, or mount point

View the data for a monitored volume, folder, mount point, or file system by executing this command.

Windows: predict -getdata <full path and folder name>

If you specify a volume for this command, all monitored paths in this volume will be reported.

Examples:

Sample Output:

predict -getdata L:\

Vol Name: L:\
Folder \test1\
Monitored Interval From <time_stamp> to <time_stamp>
Monitored area Bytes Changed 00863744 Change in MB = 0.823730 MB

Folder \test\
Monitored Interval From <time_stamp> to <time_stamp>
Monitored area Bytes Changed 60018688 Change in MB = 57.238281 MB

UNIX: cdrp -q[uery] [[-c] <fname>]

Queries replication statistics for the file system that the specified file belongs to. If a file name is not provided, the program will enumerate all mounted watched file systems and will provide statistics for each of them. You may pass a "-c" option along with the file name. This will make the tool perform continuous queries -- refreshing the screen every several seconds.

 

Reset data for a volume, folder, or mount point

Reset the data for a monitored volume, folder, mount point, or file system by executing this command.

Windows: predict -getdata <full path and folder name> -c

If you specify a volume for this command, the data for all monitored paths in this volume will be reset.

Examples:

UNIX: cdrp -r[eset] [<fname>]

Resets replication statistics for the file system that the specified file belongs to. If a file name is not provided, the program will reset replication statistics for all mounted, monitored file systems.

 

Stop monitoring

For objects not configured using CDR, stop monitoring by executing this command.

Windows: predict -remove <full path and folder name>

Examples:

UNIX: cdrp -stop <fname>

 

Using ContinuousDataReplicator in a Fan-In Configuration

The following section provides the steps required to use CDR for data replication and recovery in a Fan-In configuration based on multiple source computers and a single destination.

Before You Begin

A full understanding of the following subjects will prove helpful:

 

Data Replication for a Fan-In Configuration

Required Capability: Capabilities and Permitted Actions

To use CDR to replicate data from multiple source computers to a single destination computer:

  1. Select all the computers on which to install CDR, those designated as the source computers, and one designated as the destination computer. Verify that all selected computers meet the System Requirements, and install the ContinuousDataReplicator software on all selected computers.
    note.gif (292 bytes)
    • Review Destination volume size in Best Practices and Destination Computer Considerations.
    • For CDR on Windows:
      • The computer selected as the destination for a Fan-In configuration must have Windows 2003 installed if you want to create Recovery Points.
      • Review Log Space Requirements, accounting for the number of source computers that will be sending Replication Logs to the single destination computer.
  2. For CDR on Windows:
  3. For each source computer, do the following:
    1. Create a Replication Set. Note the following:
      • For CDR on UNIX, replication and Recovery Point options must be configured on each source Replication Set.
      • For CDR on Windows, the options specified in the previous step should not also be specified when configuring the Replication Sets, e.g., Recovery Point options should only be set on the Fan-In tab of the destination Agent Properties, not on the Replication Set Properties on the source computer.
    2. Add a Replication Pair. For all source computers configured to Fan-In to the same destination computer, every Replication Pair must use the same destination volume, but a different destination path.
    3. Optionally, configure Throttling. Note the following for Fan-In configurations:
      • Throttling can be used to allow the destination computer sufficient time to replay the logs it receives from all sources. For CDR on Windows, this can also help prevent the destination from running out of log space; for Fan-In configurations in particular, it is recommended that you configure the destination computer to start throttling the source computers when its log space runs low. For more information, see Replication Activity Throttling.
      • You might also configure the Throttling Amount on a source computer to limit the maximum amount of data (in MB/second) it can transfer to the destination, thus preventing a particular source from overwhelming the destination during periods of high I/O. However, if the source computer is throttled too much, it may not be able to transfer all its Replication Logs quickly enough, and it could run out of space. For more information, see Network Bandwidth Throttling.
    4. Start Data Replication Activity.
  4. Optionally, on the destination, create Recovery Points; for more information, see Recovery Points for a Fan-In Configuration.

Additional Recommendations

 

Recovery Points for a Fan-In Configuration

Optionally, you can create Recovery Points.

 

Additional Recommendations

 

Recovery of Data for a Fan-In Configuration

For information about recovering replicated data, see Recover Replicated Data. For Copyback procedures, see Copy Back File System Data from a Fan-In Recovery Point.

Additional Recommendations

Perform Initial Transfer of Data Without Using Baselining Phases

Before You Begin

Required Capability: Capabilities and Permitted Actions

To perform initial transfer of data without using the Baselining phases:

On Windows

  1. On the Source computer, create your Replication Pair(s) and determine the Pair ID(s) using the CDRXHelp.exe -pairs command.

    Example:

    <software_installation_path>\Base>CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pairs

    Sample output:

    91 177 L:\fromSW Z:\OutOfBand

  2. On the Source computer, query the USN for each Replication Pair source volume using one of the following:

    Example:

    <software_installation_path>\Base>CDRXHelp.exe -readUSN -cn <ClientName> -vm <InstanceName*> -pID 177

    Sample output:

    CDRXHelp 1.0 - CDR External Base Line Helper Tool

    PairId: 177

    SrcPath: L:\fromSW

    DestPath: Z:\OutOfBand

    USN: 0f4f5a68

  3. On the Source computer, set the USN for each Replication Pair to the one returned for the Replication Pair's source volume, by executing one of the following two commands:

    CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pID 177 -setUSN 177 -USN 0f4f5a68 - Use this to set Replication Pair 177 to a specific USN, in this case 0f4f5a68

    CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pID 177 -setUSN 177- Use this to set Replication Pair 177 to the current USN of the volume

    note.gif (292 bytes) If you miss this step your Replication Pair will have the default USN of 0 and when you Start the Replication Pair, a Full Re-Sync will be performed.

    Example:

    <software_installation_path>\Base> CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pID 177 -setUSN 177 -USN 0f4f5a68

    Sample output:

    CDRXHelp 1.0 - CDR External Base Line Helper Tool

    PairId: 177

    Old JournalId: ffffffffffffffff

    Old USN: ffffffffffffffff

    New JournalId: 1c625d8d392c299

    New USN: 0f4f5a68    <<< This USN is being saved in the database for the specified Replication Pair.

  4. Back up the source data.
    It is recommended that you use the Windows iDataAgent to back up the source data, and in case of applications you must use VSS with the Windows iDataAgent. See Enable VSS Backups of a Subclient for more information on enabling VSS backups on a subclient.
  5. Restore the data to the destination path(s).
  6. Start the Replication Pair(s) using Smart Re-Sync, by using the Start command. See Start/Suspend/Resume/Abort Data Replication Activity.
  7. Data replication will begin, and the Replication Pair will enter the Replicating state. All the data added/deleted or modified since the saved USN will be replicated to the destination.

* InstanceName is the name used for a CDR instance (by default it is Instance001). If multiple instances of CDR are installed use the corresponding instance name, see Multi Instancing for more information.

On Unix

  1. On the Source computer, create your Replication Pair(s) but do not start them yet.
  2. On the Source computer, set the current operating system time for each Replication Pair by using the cdrcmd -startoob -set <repset_name> -pair <source_folder> command.
    If you miss this step your Replication Pair will not have the the correct time and when you Start the Replication Pair, a Full Re-Sync will be performed.

    Example:

    <software_installation_path>/Base> cdrcmd -startoob -set MyReplicationSet -pair /MySourcePath

  3. Back up the source data.
  4. Restore the data to the destination path(s).
  5. Start the Replication Pair(s) using Smart Re-Sync, by using the Start command. Do not use the Start Full Resync command. See Start/Suspend/Resume/Abort Data Replication Activity.
  6. Data replication will begin, and the Replication Pair will enter the Replicating state. All the data added/deleted or modified since the saved OS time will be replicated to the destination.

Replicate the Destination Data Back to the Source Computer (Windows Only)

Before You Begin

Required Capability: Capabilities and Permitted Actions

To temporarily use the replica as the production data set:

  1. On the Destination computer, query and record the USN for each Replication Pair destination volume using the CDRXHelp.exe -readUSN -cn <ClientName> -vm <InstanceName*> -path L:\ command, which returns the current USN of the specified volume. All Replication Pairs using this volume as a destination will share the same USN.

    Example:

    There are three Replication Pairs:
       E:\ => L:\E_drive
       F:\ => L:\F_drive
       N:\ => M:\N_drive

    Query the USNs of the L: and M: volumes (the first two Replication Pairs use the same destination drive, L:, and will thus use the same USN) by typing the following commands:

    Record both USNs for use later in this procedure.

  2. The replica on the Destination computer can now be used as the production data set.

When the original Source computer is operational again, proceed to the next section.
 

To replicate data back to the original Source computer:

  1. On the Source computer, record your Replication Pair configuration information, then delete the Replication Pair(s) and Replication Set(s). See Delete a Replication Pair and Delete a Replication Set.
  2. On the Destination computer, create a Replication Set and Replication Pair(s) -- reversing the source and destination for each Replication Pair that existed on the original Source computer -- and determine the Pair ID(s) using the CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pairs command. See Create a Replication Set and Add or Edit a Replication Pair.

    Do not start the Replication Pair(s) yet.

    Example:
    Using the same example from Step 2, create three Replication Pairs on the Destination computer:
       L:\E_drive => E:\ 
       L:\F_drive => F:\
       M:\N_drive => N:\

    Determine the Replication Pair ID(s) using the CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pairs command:

    <software_installation_path>\Base> CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pairs

    Sample output:
    REPID PAIRID  SrcPath      DestPath
    91    177     L:\E_drive   E:\
    91    180     L:\F_drive   F:\
    92    183     M:\N_drive   N:\

  3. On the Destination computer, set the USN for each Replication Pair to the one returned for the original Replication Pair's destination volume (the USNs you recorded in Step 2) by executing the following command:

    CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pID <PAIRID> -setUSN <PAIRID> -USN <some_USN> - sets a Replication Pair with a Pair ID <PAIRID> to a specific USN, <some_USN>.

    If you miss this step your Replication Pair will have the default USN of 0 and when you start the Replication Pair, a Full Re-Sync will be performed.

    Example:

    Using the same example from Steps 2 and 4, execute the following three commands:

    <software_installation_path>\Base> CDRXHelp.exe -cn <ClientName> -vm <InstanceName*> -pID 177 -setUSN 177 -USN 0f4f5a68
    <software_installation_path>\Base> CDRXHelp.exe -cn <ClientName> -vm <InstanceName    *> -pID 180 -setUSN 180 -USN 0f4f5a68
    <software_installation_path>\Base> CDRXHelp.exe -cn <ClientName> -vm <InstanceName    *> -pID 183 -setUSN 183 -USN 0f4f6b46

    Sample output:
    CDRXHelp 1.0 - CDR External Base Line Helper Tool
    PairId: 177
    Old JournalId: ffffffffffffffff
    Old USN: ffffffffffffffff
    New JournalId: 1c625d8d392c299
    New USN: 0f4f5a68

  4. By default, orphan files will be automatically deleted. If there were files on the original Source computer which were never replicated to the Destination computer, you may not want such files to be deleted as orphans. See View Orphan Files and Data Replication - Orphan Files.
  5. On the Destination computer, start the Replication Pair(s) using Smart Re-Sync, by using the Start command. See Start/Suspend/Resume/Abort Data Replication Activity.
  6. Baselining will begin; all the data added, deleted, or modified since the saved USN will be copied back to the original Source computer.
  7. When the Baselining phases end, stop using the Destination computer as a production server and create a Consistent Recovery Point to ensure all the data has been replicated back to the source. See Create a Recovery Point Using CDR.
  8. On the Destination computer, abort and delete the Replication Pair(s). See Start/Suspend/Resume/Abort Data Replication Activity and Delete a Replication Pair. Also, delete the Replication Sets; see Delete a Replication Set.
    When the Replication Set is deleted, any Recovery Points or Consistent Recovery Points that were created from the Destination will be deleted as well, which is necessary in order for SmartSync to succeed when you start replication on the original Source computer again. If you want to preserve the data in such Recovery Points, back them up before deleting the Replication Set. See Back up a Recovery Point Using CDR.
  9. On the original Source computer, recreate the original Replication Set and Replication Pair(s). See Create a Replication Set and Add or Edit a Replication Pair.

    Do not start the Replication Pair(s) yet.

  10. To avoid transferring all the data again, set the USN for each Replication Pair before you start replication. Perform the following on the original Source computer:
  11. On the original Source computer, start the Replication Pair(s) using Smart Re-Sync, and begin using the Source computer as the production server again.

* InstanceName is the name used for a CDR instance (by default it is Instance001). If multiple instances of CDR are installed use the corresponding instance name, see Multi Instancing for more information.

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