Recovery From a Hot Backup

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Recovery From a Hot Backup

Hot Backup

A hot backup is a backup that is performed while the database is being updated. The steps that must be taken to create a usable hot backup are described in 21.2, “Backup Procedures”.

Recovery Procedures

Following are two approaches to recovery from a hot backup. The first involves the use of both the ROLLBACK and ROLLFORWARD utility statements; the second involves two executions of the ROLLFORWARD utility statement. Either approach can be used to successfully recover from a hot backup; however certain conditions must be satisfied to use the second approach.

Note: For additional considerations associated with specific types of failure, refer to later sections in this chapter.

InDoubt Transaction Considerations

With either approach, there is no need to take any special action with regard to incomplete InDoubt transactions during the first recovery operation (during a ROLLBACK in approach 1 or the first ROLLFORWARD in approach 2), since the utility will handle them correctly.

However, depending on the nature of the recovery, you may need to take some action for InDoubt transactions that remain at the end of the final ROLLFORWARD operation. For more information, see 21.4.2, “Incomplete Transactions and Manual Recovery”.

Restore Procedure 1

This approach can always be used to recover from a hot backup provided that the correct procedures were followed when the backup was taken and the necessary journal and backup files are available.

Action	Steps
Copy the files that need to be recovered from the backup. When required: Always.	Execute the RESTORE utility statement using the FILE option or another comparable utility.
Identify: The quiesce point that was taken at the beginning of the backup procedure. The archive journal files created since this quiesce point up to and including the one created at the end of the backup procedure. All archive journal files created since the quiesce point up to the point of failure. When required: Always.	Use the PRINT JOURNAL utility statement, or if the quiesce point was established using the DCMT QUIESCE command, examine the operating system log for the DC/UCF system on which the DCMT command was issued.
Consolidate, in the sequence in which they were created, the archive journal files created between the quiesce point and the end of the backup procedure. When required: This step is necessary only under the following conditions: In z/OS environments if more than one input journal file must be processed. In a data sharing environment, if the SEQUENTIAL option will be specified on the subsequent ROLLBACK utility statement and more than one member's journal images must be processed.	Execute one of the following and use as input the properly concatenated set of archive files: FIX ARCHIVE utility statement MERGE ARCHIVE utility statement Another comparable utility If consolidating archive files from multiple members and the subsequent rollback will be executed with the SEQUENTIAL option, use the MERGE ARCHIVE utility statement. Note: For more information, see Data Sharing Recovery Considerations. This and the subsequent step can be combined by using a sort utility to do the consolidation unless the use of MERGE ARCHIVE is required.
If backward read is not supported, presort the journal blocks created between the quiesce point and the end of the backup procedure in reverse sequence. Multiple archive files may be consolidated into a single sorted output file. When required: This step is necessary in a z/VM environment or if the journal files reside on devices such as disk or 3490s that do not support backward read.	Execute the sort utility and use as input either a set of archive journal files or the consolidated journal file produced in the preceding step. Note: For the sort parameters to use, see the ROLLBACK utility statement in the CA IDMS Utilities Guide.
Remove from the restored files the effects of all updates made between the quiesce point and the end of the backup process. When required: Always	Execute the ROLLBACK utility statement specifying the HOTBACKUP option and using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created. If the quiesce point for the affected areas does not coincide with the start of the input (or the end of the input if it was sorted in reverse sequence), use the STOP TIME parameter to identify the quiesce point. If STOP TIME is specified, also specify ACTIVE; otherwise specify ALL. If backward read is not supported for the device on which the input journal file resides, specify ROLLBACK3490 in the SYSIDMS parameter file associated with the ROLLBACK job step. This parameter is not necessary in a z/VM environment. If a consolidated journal file is not used as input in z/OS environments, specify the SORTED option.
Consolidate, in the sequence in which they were created, the archive journal files created since the quiesce point established at the start of the backup procedure. When required: This step is necessary only under the following conditions: In z/OS environments, if the subsequent ROLLFORWARD utility statement will be executed with the SEQUENTIAL option and more than one archive journal file must be processed. In a data sharing environment, if more than one member has updated the affected areas and the subsequent ROLLFORWARD utility statement will be executed with either the SEQUENTIAL or the ALL and STOP TIME options.	Execute one of the following and use as input the properly concatenated set of archive files: FIX ARCHIVE utility statement MERGE ARCHIVE utility statement EXTRACT JOURNAL utility statement Another comparable utility If consolidating archive files from multiple members and the subsequent rollforward will be executed with either the SEQUENTIAL or the ALL and STOP TIME parameters, use the MERGE ARCHIVE utility statement. Note: For more information, see Data Sharing Recovery Considerations. If recovery also involves local mode journal files, the MERGE ARCHIVE utility statement can be used to consolidate local mode journal files and archive files. Note: For more information, see Recovery Procedures for Mixed-Mode Operations.
Reapply to the restored files all updates made since the quiesce point established at the beginning of the backup procedure. When required: Always.	Execute the ROLLFORWARD utility statement using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created. If the journal files were consolidated using the EXTRACT JOURNAL utility, specify the FROM EXTRACT option. If FROM EXTRACT is not specified, then the following considerations apply: Specify the SORTED option unless there is insufficient disk space available. SORTED must be specified if: A consolidated journal file is not used as input in z/OS environments and more than one archive file must be processed. The input journal file is on a device, such as a disk or a 3490 that does not support reading backwards. Running ROLLFORWARD in a z/VM environment. If the SEQUENTIAL option is used and the quiesce point for the affected areas does not coincide with the start of the first input file, use the START TIME parameter to identify the quiesce point.

Action

Steps

Copy the files that need to be recovered from the backup.

When required: Always.

Execute the RESTORE utility statement using the FILE option or another comparable utility.

Identify:

The quiesce point that was taken at the beginning of the backup procedure.
The archive journal files created since this quiesce point up to and including the one created at the end of the backup procedure.
All archive journal files created since the quiesce point up to the point of failure.

When required: Always.

Use the PRINT JOURNAL utility statement, or if the quiesce point was established using the DCMT QUIESCE command, examine the operating system log for the DC/UCF system on which the DCMT command was issued.

Consolidate, in the sequence in which they were created, the archive journal files created between the quiesce point and the end of the backup procedure.

When required: This step is necessary only under the following conditions:

In z/OS environments if more than one input journal file must be processed.

In a data sharing environment, if the SEQUENTIAL option will be specified on the subsequent ROLLBACK utility statement and more than one member's journal images must be processed.

Execute one of the following and use as input the properly concatenated set of archive files:

FIX ARCHIVE utility statement
MERGE ARCHIVE utility statement
Another comparable utility

If consolidating archive files from multiple members and the subsequent rollback will be executed with the SEQUENTIAL option, use the MERGE ARCHIVE utility statement.

Note: For more information, see Data Sharing Recovery Considerations.

This and the subsequent step can be combined by using a sort utility to do the consolidation unless the use of MERGE ARCHIVE is required.

If backward read is not supported, presort the journal blocks created between the quiesce point and the end of the backup procedure in reverse sequence.

Multiple archive files may be consolidated into a single sorted output file.

When required: This step is necessary in a z/VM environment or if the journal files reside on devices such as disk or 3490s that do not support backward read.

Execute the sort utility and use as input either a set of archive journal files or the consolidated journal file produced in the preceding step.

Note: For the sort parameters to use, see the ROLLBACK utility statement in the CA IDMS Utilities Guide.

Remove from the restored files the effects of all updates made between the quiesce point and the end of the backup process.

When required: Always

Execute the ROLLBACK utility statement specifying the HOTBACKUP option and using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created.

If the quiesce point for the affected areas does not coincide with the start of the input (or the end of the input if it was sorted in reverse sequence), use the STOP TIME parameter to identify the quiesce point.

If STOP TIME is specified, also specify ACTIVE; otherwise specify ALL.

If backward read is not supported for the device on which the input journal file resides, specify ROLLBACK3490 in the SYSIDMS parameter file associated with the ROLLBACK job step. This parameter is not necessary in a z/VM environment.

If a consolidated journal file is not used as input in z/OS environments, specify the SORTED option.

Consolidate, in the sequence in which they were created, the archive journal files created since the quiesce point established at the start of the backup procedure.

When required: This step is necessary only under the following conditions:

In z/OS environments, if the subsequent ROLLFORWARD utility statement will be executed with the SEQUENTIAL option and more than one archive journal file must be processed.

In a data sharing environment, if more than one member has updated the affected areas and the subsequent ROLLFORWARD utility statement will be executed with either the SEQUENTIAL or the ALL and STOP TIME options.

Execute one of the following and use as input the properly concatenated set of archive files:

FIX ARCHIVE utility statement
MERGE ARCHIVE utility statement
EXTRACT JOURNAL utility statement
Another comparable utility

If consolidating archive files from multiple members and the subsequent rollforward will be executed with either the SEQUENTIAL or the ALL and STOP TIME parameters, use the MERGE ARCHIVE utility statement.

Note: For more information, see Data Sharing Recovery Considerations.

If recovery also involves local mode journal files, the MERGE ARCHIVE utility statement can be used to consolidate local mode journal files and archive files.

Note: For more information, see Recovery Procedures for Mixed-Mode Operations.

Reapply to the restored files all updates made since the quiesce point established at the beginning of the backup procedure.

When required: Always.

Execute the ROLLFORWARD utility statement using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created.

If the journal files were consolidated using the EXTRACT JOURNAL utility, specify the FROM EXTRACT option.

If FROM EXTRACT is not specified, then the following considerations apply:

Specify the SORTED option unless there is insufficient disk space available. SORTED must be specified if:
A consolidated journal file is not used as input in z/OS environments and more than one archive file must be processed.
The input journal file is on a device, such as a disk or a 3490 that does not support reading backwards.
Running ROLLFORWARD in a z/VM environment.

If the SEQUENTIAL option is used and the quiesce point for the affected areas does not coincide with the start of the first input file, use the START TIME parameter to identify the quiesce point.

Restore Procedure 2

The use of this approach requires that:

Two quiesce points were established during the hot backup procedure
Backward read is supported for the input journal files. Backward read is not available in z/VM environments nor when the journal files reside on disk or a device such as a 3490

If either of these conditions are not satisfied, the first recovery approach must be followed.

Action	Steps
Copy the files that need to be recovered from the backup When required: Always.	Execute the RESTORE utility statement using the FILE option or another comparable utility.
Identify the two quiesce points that were taken during the backup process. Also identify the archive journal files that were created between those quiesce points and after the second quiesce point. When required: Always.	Use the PRINT JOURNAL utility statement, or if the quiesce point was established using the DCMT QUIESCE command, examine the operating system log for the DC/UCF system on which the DCMT command was issued.
Consolidate, in the sequence in which they were created, the archive journal files created between the two quiesce points established during the backup procedure. When required: This step is necessary only in z/OS, and data sharing environments if more than one archive journal file must be processed.	Execute one of the following and use as input the properly concatenated set of archive files: FIX ARCHIVE utility statement MERGE ARCHIVE utility statement Another comparable utility Note: If consolidating archive files from multiple data sharing members, use the MERGE ARCHIVE utility statement. For more information, see Data Sharing Recovery Considerations.
Reapply to the restored files all updates made between the two quiesce points.	Execute the ROLLFORWARD utility statement specifying the SEQUENTIAL option and using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created. If the first quiesce point for the affected areas does not coincide with the start of the first input file, use the START TIME parameter to identify the quiesce point. If the second quiesce point does not coincide with the end of the last input file, use the STOP TIME parameter to identify the second quiesce point. Note: Output from the EXTRACT utility statement cannot be used to apply the images during this step.
Consolidate, in the sequence in which they were created, the archive journal files created after the second quiesce point established during the backup procedure. When required: This step is necessary only under the following conditions: In z/OS environments, if the subsequent ROLLFORWARD utility statement will be executed with the SEQUENTIAL option and more than one archive journal file must be processed. In a data sharing environment, if more than one member has updated the affected areas and the subsequent ROLLFORWARD utility statement will be executed with either the SEQUENTIAL or the ALL and STOP TIME options.	Execute one of the following and use as input the properly concatenated set of archive files: FIX ARCHIVE utility statement MERGE ARCHIVE utility statement EXTRACT JOURNAL utility statement Another comparable utility If consolidating archive files from multiple members and the subsequent rollforward will be executed with either the SEQUENTIAL or the ALL and STOP TIME parameters, use the MERGE ARCHIVE utility statement. Note: For more information, see Data Sharing Recovery Considerations. If recovery also involves local mode journal files, the MERGE ARCHIVE utility statement can be used to consolidate local mode journal files and archive files. Note: For more information, see Recovery Procedures for Mixed-Mode Operations.
Reapply to the restored files, all updates made since the second quiesce point. Note: Updates made prior to the second quiesce point may also be reapplied during this step; however there is no need to do so. When required: Always.	Execute the ROLLFORWARD utility statement using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created. If the journal files were consolidated using the EXTRACT JOURNAL utility, specify the FROM EXTRACT option. If FROM EXTRACT is not specified, then the following considerations apply: Specify the SORTED option unless there is insufficient disk space available to perform the sort. SORTED must be specified if a consolidated journal file is not used as input in z/OS environments and more than one archive file must be processed. If the SEQUENTIAL option is used and the quiesce point for the affected areas does not coincide with the start of the first input file, use the START TIME parameter to identify the quiesce point.

Action

Steps

Copy the files that need to be recovered from the backup

When required: Always.

Execute the RESTORE utility statement using the FILE option or another comparable utility.

Identify the two quiesce points that were taken during the backup process. Also identify the archive journal files that were created between those quiesce points and after the second quiesce point.

When required: Always.

Consolidate, in the sequence in which they were created, the archive journal files created between the two quiesce points established during the backup procedure.

When required: This step is necessary only in z/OS, and data sharing environments if more than one archive journal file must be processed.

Execute one of the following and use as input the properly concatenated set of archive files:

FIX ARCHIVE utility statement
MERGE ARCHIVE utility statement
Another comparable utility
Note: If consolidating archive files from multiple data sharing members, use the MERGE ARCHIVE utility statement. For more information, see Data Sharing Recovery Considerations.

Reapply to the restored files all updates made between the two quiesce points.

Execute the ROLLFORWARD utility statement specifying the SEQUENTIAL option and using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created.

If the first quiesce point for the affected areas does not coincide with the start of the first input file, use the START TIME parameter to identify the quiesce point.

If the second quiesce point does not coincide with the end of the last input file, use the STOP TIME parameter to identify the second quiesce point.

Note: Output from the EXTRACT utility statement cannot be used to apply the images during this step.

Consolidate, in the sequence in which they were created, the archive journal files created after the second quiesce point established during the backup procedure.

When required: This step is necessary only under the following conditions:

In z/OS environments, if the subsequent ROLLFORWARD utility statement will be executed with the SEQUENTIAL option and more than one archive journal file must be processed.
In a data sharing environment, if more than one member has updated the affected areas and the subsequent ROLLFORWARD utility statement will be executed with either the SEQUENTIAL or the ALL and STOP TIME options.

Execute one of the following and use as input the properly concatenated set of archive files:

FIX ARCHIVE utility statement
MERGE ARCHIVE utility statement
EXTRACT JOURNAL utility statement
Another comparable utility

Note: For more information, see Data Sharing Recovery Considerations.

If recovery also involves local mode journal files, the MERGE ARCHIVE utility statement can be used to consolidate local mode journal files and archive files.

Note: For more information, see Recovery Procedures for Mixed-Mode Operations.

Reapply to the restored files, all updates made since the second quiesce point.

Note: Updates made prior to the second quiesce point may also be reapplied during this step; however there is no need to do so.

When required: Always.

Execute the ROLLFORWARD utility statement using either the consolidated journal file or individual archive files concatenated in the sequence in which they were created.

If the journal files were consolidated using the EXTRACT JOURNAL utility, specify the FROM EXTRACT option.

If FROM EXTRACT is not specified, then the following considerations apply:

Specify the SORTED option unless there is insufficient disk space available to perform the sort. SORTED must be specified if a consolidated journal file is not used as input in z/OS environments and more than one archive file must be processed.
If the SEQUENTIAL option is used and the quiesce point for the affected areas does not coincide with the start of the first input file, use the START TIME parameter to identify the quiesce point.