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Sharding: Restore

{NOTE: }

{NOTE/}

{PANEL: Restore}

To restore a sharded database, we need to:

Set Paths to Backup Files Locations

When a shard stores a backup file, it may store it locally (on the shard node's storage) or remotely (supported platforms currently include S3 Buckets, Azure Blobs, and Google cloud).

To restore the backup files, we need to provide the restore process with each shard's backup folder location.
The shards' backup folder locations, and additional data regarding the backups, are provided in a dictionary of SingleShardRestoreSetting objects.

SingleShardRestoreSetting
{CODE restore_SingleShardRestoreSetting@Sharding\ShardingBackupAndRestore.cs /}

  • Parameters:

    Parameter Value Functionality
    ShardNumber int The shard number that will be given to the restored shard.
    should normally be similar to the original shard number.
    NodeTag string The node to restore the shard on.
    FolderName string The name of the folder that holds the backup file/s.
    LastFileNameToRestore string Last incremental backup file to restore.
    If omitted, restore all backup files in folder.

    {WARNING: } When setting ShardNumber, please make sure that all shards are given the same numbers they had when they were backed-up.
    Giving a restored shard a number different than its original number will place buckets on the wrong shards and cause mapping errors.

    E.g., a backup of shard 1 must be restored as shard 1: ShardNumber = 1
    {WARNING/}

    {WARNING: } When restoring a local shard backup, make sure that the backup file resides on the node that the shard's NodeTag property is set to, so the restore process can find the file.

    E.g., if a backup file that's been produced by node A is now restored to node B (NodeTag = "B"), place the backup file in the backup folder of node B before initiating the restore operation.
    {WARNING/}

Define a Restore Configuration

To restore the database, we pass the Restore Operation a configuration object.

  • The configuration object inherits properties from the RestoreBackupConfigurationBase class (discussed below) and defines additional sharding-specific settings.

  • We choose what configuration object to pass the restore operation, by the backup files' location.
    The backup files may be located locally (on each shard machine storage) or remotely (in a cloud location).

    Configuration Object Backup Location Additional Properties
    RestoreBackupConfiguration Local shard storage None (see example)
    RestoreFromS3Configuration AWS S3 Bucket S3Settings (see S3 example)
    RestoreFromAzureConfiguration MS Azure Blob AzureSettings (see Azure example)
    RestoreFromGoogleCloudConfiguration Google Cloud Bucket GoogleCloudSettings (see Google Cloud example)

RestoreBackupConfigurationBase

RestoreBackupConfigurationBase is a parent class to all the configuration types mentioned above, allowing you to set backups encryption settings among other options.
{CODE restore_RestoreBackupConfigurationBase@Sharding\ShardingBackupAndRestore.cs /}

  • Parameters:

    Parameter Value Functionality
    DatabaseName string Name for the new database.
    LastFileNameToRestore
    (Optional -
    omit for default)    		 string Last incremental backup file to restore.
    Ignored when restoring a sharded database.
    SingleShardRestoreSetting.LastFileNameToRestore used instead, per shard.
    DataDirectory
    (Optional -
    omit for default)    		 string The new database data directory.

    Default folder:
    Under the "Databases" folder
    In a folder carrying the restored database name.
    EncryptionKey
    (Optional -
    omit for default)    		 string A key for an encrypted database.

    Default behavior:
    Try restoring as if DB is unencrypted.
    DisableOngoingTasks
    (Optional -
    omit for default)    		 boolean true - disable ongoing tasks when Restore is complete.
    false - enable ongoing tasks when Restore is complete.

    Default: false
    Ongoing tasks will run when Restore is complete.
    SkipIndexes
    (Optional -
    omit for default)    		 boolean true - disable indexes import,
    false - enable indexes import.

    Default: false
    Restore all indexes.
    ShardRestoreSettings ShardedRestoreSettings a dictionary of SingleShardRestoreSetting instances defining paths to backup locations
    {CODE restore_ShardedRestoreSettings@Sharding\ShardingBackupAndRestore.cs /}
    BackupEncryptionSettings BackupEncryptionSettings Backup Encryption Settings

    {NOTE: } Verify that RavenDB has full access to the backup locations and database files.
    Make sure your server has write permission to DataDirectory.
    {NOTE/}

Run RestoreBackupOperation with the Restore Configuration

Pass the configuration object you defined to the RestoreBackupOperation store operation to restore the database.
{CODE restore_RestoreBackupOperation@Sharding\ShardingBackupAndRestore.cs /}

  • Instead of RestoreBackupConfigurationBase, use the configuration object you prepared:
    • RestoreBackupConfiguration for locally-stored backups
    • RestoreFromS3Configuration to restore from S3
    • RestoreFromAzureConfiguration to restore from Azure
    • RestoreFromGoogleCloudConfiguration to restore from Google Cloud

Examples

Here are examples for restoring a sharded database using backup files stored locally and remotely.

{CODE-TABS} {CODE-TAB:csharp:Local_Storage restore_local-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TAB:csharp:S3_Bucket restore_s3-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TAB:csharp:Azure_Blob restore_azure-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TAB:csharp:Google_Cloud restore_google-cloud-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TABS/}

{PANEL/}

{PANEL: Restoring to a Selected Restore Point}

The default procedure

When a full backup is created, (for either a non sharded database or for any shard of a sharded database), a backup folder is created to contain it.
When incremental backups are created, they are stored in the folder of the last full backup.
To restore a backup, its folder name is provided. By default, the full backup stored in this folder will be restored, as well as all the incremental backups that were added to it over time.

Restoring a Non-sharded database to a selected restore point

Restoring a Sharded database to a selected restore point

  • When a sharded database is restored, RestoreBackupConfiguration.BackupLocation and RestoreBackupConfiguration.LastFileNameToRestore mentioned above are overridden by per-shard settings.

  • To restore the database of a particular shard up to a selected restore point simply add ShardRestoreSettings.SingleShardRestoreSetting.LastFileNameToRestore to the shard configuration and fill it with the name of the last incremental backup to restore.

  • Example:
    {CODE-TABS} {CODE-TAB:csharp:Local_Storage singleShardSettings_restore_local-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TAB:csharp:S3_Bucket singleShardSettings_restore_s3-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TAB:csharp:Azure_Blob singleShardSettings_restore_azure-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TAB:csharp:Google_Cloud singleShardSettings_restore_google-cloud-settings@Sharding\ShardingBackupAndRestore.cs /} {CODE-TABS/}

{PANEL/}

{PANEL: Restore Options Summary}

Option Supported on a Sharded Database Comment
Restore from local shard storage Yes
Restore from a remote location Yes Define a restore configuration with S3, Azure, or Google Cloud settings.
Restore a sharded database backup
to a sharded database		 Yes
Restore a sharded database backup
to a non-sharded database		 Yes
Restore a non-sharded database backup
to a sharded database		 No A backup created for a non-sharded database CANNOT be restored to a sharded database.
Restore a Full database backup Yes
Restore a Partial database backup Yes
Restore a Logical database backup Yes
Restore a Snapshot database backup No A snapshot backup CANNOT be restored by a sharded database.
Restore backed-up shards in a different order than the original No Always restore the shards in their original order.

{PANEL/}

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