Storage Checkpoint Allocation Policies

VERITAS File System provides Multi-Volume File Systems (MVS) when used in conjunction with the Volumes Set feature in VERITAS Volume Manager. A volume set is a container for multiple different volumes. MVS enables creation of a single file system over multiple volumes, each volume with properties of its own. This helps administrators specify which data goes on which volume types. For more details about MVS, see VERITAS Volume Manager Administrator's Guide. Setting up a storage configuration for MVS operations is a system administrator's responsibility and requires superuser (root) privileges.

Multi-Volume File Systems provide, a database administrator, through the SFUA checkpoint administration interface, the ability to create Storage Checkpoint Allocation Policies. A Storage Checkpoint Allocation policy specifies a list of volumes and the order in which to attempt allocations. Once defined, a database administrator can use these policies to:

• Control where the storage checkpoint should be created enabling separation of metadata and data of a storage checkpoint to different volumes.
• Separate storage checkpoints so that data allocated to a storage checkpoint is isolated from the primary file system. This helps control the space used by the checkpoint and prevents the checkpoint from fragmenting the space in the primary fileset.

When policies are assigned to a storage checkpoint, the database administrator must specify the mapping to both metadata and file data. If no policies are specified for the storage checkpoint, the data is placed randomly within the primary file system. Data and metadata of storage checkpoints can have different policies assigned to them or use the same policy to be applied to data and metadata. Multiple checkpoints can be assigned the same checkpoint allocation policy. A partial policy is also allowed; a partial policy means that the policy does not exist on all file systems used by the database.

Once the policy is assigned to checkpoints, the allocation mechanism attempts to satisfy the request from each device in the policy in the order the devices are defined. If the request cannot be satisfied from any of the devices in the policy, the request will fail, even if other devices exist in the file system which have space. Only those devices can provide allocation that are listed in the policy. This implementation is the mechanism for preventing allocation requests from using space in other devices which are not specified in the policy. It is recommended that you allocate sufficient space for the volumes defined in the Storage Checkpoint policy or update the policy to include additional volumes. This also helps in retaining the old Storage Checkpoints.

Once the assigned policy is deleted, the allocation for metadata and file data for subsequent requests of storage checkpoint will return to the no policy assigned state.

Usage Notes

• Since the checkpoint policies feature is associated with MVS file system, it is available only on file systems using disk layout Version 6.
• Storage checkpoint allocation policy requires VxVM Volume Set and VxFS Multi-Volume File Systems features to be enabled. These features are included in the Enterprise Edition of Storage Foundation. Refer to the Multi-Volume File System chapter in the VERITAS File System Administrator's Guide, for creating Volume Sets and MVS file systems for the primary file systems used by the database datafiles.
• Data allocation is done by the volumes in the order that was assigned in the policy.
• The maximum length of an checkpoint policy name is 64 characters.

Using Storage Checkpoint Allocation Policies

You can use the dbed_ckptpolicy command to administrate the storage checkpoint allocation policies. For detailed information on administrating Storage Checkpoint Policy via the CLI, see VERITAS Storage Foundation for Oracle Command Line Interface.

Usage Notes

See the dbed_ckptpolicy(1M) and dbed_ckptcreate(1M) manual pages for more information. dbed_ckptpolicy command need to be executed by the Oracle database administrator.

In the following example, the file systems for database datafiles are set up as follows:

• Two MVS file systems /mvsfs/v1 and /mvsfs/v2 used for database datafiles.
• File system /mvsfs/v1 is created on volume set mvsvset1.
• File system /mvsfs/v2 is created on volume set mvsvset2.
• Volume set mvsvset1 contains volumes mvsv1, mvsv2, and mvsv3.
• Volume set mvsvset2 contains volumes mvsv4 and mvsv5.

Usage

Use the dbed_ckptpolicy command with the following options.

Where options could be any of the following parameters:

Creating a Storage Checkpoint Allocation policy

  To create a Storage Checkpoint allocation policy

Use the dbed_ckptpolicy command as follows:

Example

In the following example, the database name is PROD and the Storage Checkpoint allocation policy that is created is named ckpt_sample.

Output similar to the following is displayed.

Assigning a Storage Checkpoint Allocation policy

You can use either of the following methods to assign an allocation policy to a Storage Checkpoint:

• Use the dbed_ckptpolicy command to assign allocation policies to an existing storage checkpoint.
• Use [ -p ckpt_data_policy[,ckpt_metadata_policy]] option in dbed_ckptcreate command to supply policies when executed.

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  Note    dbed_ckptcreate command automaticlly assigns the policies when the storage checkpoint is created.

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  To assign an allocation policy to an existing Storage Checkpoint

The following procedure uses dbed_ckptpolicy to assign an allocation policy to an existing Storage Checkpoint. This example uses PROD as the database name and Checkpoint_1096060202 as a sample Storage Checkpoint.

1. Create an online Storage Checkpoint for database PROD.
    $ dbed_ckptcreate -S PROD -H ORACLE_HOME -o online
   

   As a result, Checkpoint_1096060202 is created.

2. Assign a Storage Checkpoint policy to the Checkpoint_1096060202.
   $ dbed_ckptpolicy -S PROD -n -o assign -c Checkpoint_1096060202 \
   -p ckpt_data,ckpt_metadata
3. Display the details of the Storage Checkpoint allocation policy assigned to Checkpoint_1096060202.
    $ dbed_ckptpolicy -S PROD -n -o display -c Checkpoint_1096060202

   Output similar to the following is displayed:

   
   Storage Checkpoint              File System         Data Policy         Meta Data Policy
   ------------------               ------------          ------------ ------------------
   Checkpoint_1096060202               /mvsfs/v2        ckpt_data         ckpt_metadata
   Checkpoint_1096060202               /mvsfs/v1        ckpt_data         ckpt_metadata

  To assign an allocation policy to a new Storage Checkpoint

1. Use dbed_ckpcreate to assign an allocation policy to a new Storage Checkpoint.
     $ dbed_ckptcreate -S PROD -H -o online -p ckpt_data,ckpt_metadata

   As a result, a Storage Checkpoint allocation policy is assigned to Checkpoint_1096060122, which is a new Storage Checkpoint.

2. Display the details of the Storage Checkpoint allocation policy assigned to checkpoint 1096060122.
     $ dbed_ckptpolicy -D PROD -n -o display -c Checkpoint_1096060122

Output similar to the following is displayed:

Displaying a Storage Checkpoint Allocation policy

  To display a Storage Checkpoint allocation policy

Use the -o display option to list all the Storage Checkpoint allocation policies contained in the file systems used by the database.

Usage

Output similar to the following is displayed:

  To display Storage Checkpoint Allocation Policy information

Use the -o display -p checkpointpolicy_name option to display information related to a specific Storage Checkpoint allocation policy.

Usage

Output similar to the following is displayed:

  To display the allocation policies assigned to a Storage Checkpoint

Use the -o display -c checkpoint_xxxxxxxxx option to display the allocation policies assigned to the Storage Checkpoint.

Usage

Output similar to the following is displayed:

Updating a Storage Checkpoint Allocation Policy

  To update a Storage Checkpoint Allocation Policy

Use the -o update -p checkpoint_policy_name option to update an allocation policy.

Example

Output similar to the following is displayed:

Removing a Storage Checkpoint Allocation Policy

  To remove a Storage Checkpoint Allocation Policy

Use the following command to remove a Storage Checkpoint allocation policy:

Converting from Regular VxFS file system to MVS

The following procedure describes the conversion of a regular VxFS file system to MVS file system and optionally add new volume to it. Converting a regular VxFS to MVS requires superuser (root) privileges. For further details on creating and administrating the VxVM Volume Sets and VxFS Multi-Volume Files System, refer to the VERITAS Volume Manager Administrator's Guide and VERITAS File System Administrator's Guide.

  To convert from a regular VxFS file system to MVS:

1. Select a non-MVS file system to convert to MVS and unmount it.
   # umount /mnt1
2. Create the volume set.
   # vxvset -g dgname make myvset old_vol
3. Mount the volume set.
   # mount -F vxfs /dev/vx/dsk/dgname/myvset /mnt1
4. Upgrade the volume set's file system to Version 6 disk layout. See VERITAS File System Installation Guide and the vxfsconvert(1M) and vxupgrade(1M) manual pages for information on upgrading VxFS disk layouts.
   # vxupgrade -n 6 /mnt1
5. Add the new volume to the volume set.
   # vxvset -g dgname addvol myvset new_vol
6. Add the new volume to the file system. You must specify the size of the volume.
   # fsvoladm add /mnt1 new_vol 2g

   where new_vol is the name of the newly added volume and 2g is the size of the volume.

7. Verify the new volume in the file system.
   # fsvoladm list /mnt1