Sharded and Non-Sharded Backup Tasks
From a user's perspective, backing up a sharded database is done by
defining and running a single backup task, just like it is done
with a non-sharded database.
Behind the scenes, though, each shard backs up its own slice of the
database independently from other shards.
Distributing the backup responsibility between the shards allows
RavenDB to speed up the backup process and keep backup files in
manageable proportions no matter what the overall database size is.
Non-Sharded DB Backup Tasks
- A complete replica of the database is kept by each cluster node.
- Any node can therefore be made
for backups by the cluster.
- The responsible node runs the backup task periodically to create
a backup of the entire database.
Sharded DB Backup Tasks
- Each shard hosts a unique part of the database, so no single node
can create a backup of the entire database.
- After a user defines a backup task, RavenDB automatically creates
one backup task per shard, based on the user-defined task.
This operation is automatic and requires no additional actions
from the user.
- Each shard appoints one of its nodes
responsible for the execution of the shard's backup task.
- Each shard backup task can keep the shard's database
locally (on the shard machine), and/or remotely (on one
or more cloud destinations).
- A backup task can store backups on multiple destinations,
e.g. locally, on an S3 bucket, and on an Azure blob.
- To restore
the entire database, the restore process is provided with
the locations of the backup folders used by all shards.
- When restoring the database, the user doesn't have to restore
all shard backups. It is possible, for example, to restore only
one of the shards. Using this flexibility, a sharded database
can easily be split into several databases.
Backup Storage: Local and Remote
Backup files can be stored locally and remotely.
Find a code example here.
A shard's backup task may keep backup data locally,
using the node's local storage.
backup files that were stored locally requires the user to provide
the restore process with the location of the backup folder on each
Backups can also be kept remotely. All shards will transfer
the backup files to a common location, using one of the currently
- Azure Blob Storage
- Amazon S3 Storage
- Google Cloud Platform
backup files that were stored remotely requires the user to provide
the restore process with each shard's backup folder location.
Backup Files Extension and Structure
backup files use the same internal structure as the
files that Studio
create when exporting data.
It is therefore possible to not only restore
but also import backup files using studio
Read more about this feature here.
A shard backup task can create a
backup cannot be created for a sharded database.
Logical backups created for a sharded database can be restored into
both sharded and non-sharded databases.
A shard backup task can create
a Full backup
with the entire content of the shard, or an
with just the difference between the current database data and the last backed-up data.
Backup files created for a sharded database generally follow the same naming
as non-sharded database backups.
Each shard keeps its backup files in a folder whose name consists of:
- Date and Time (when the folder was created)
- Database Name
- Shard Number
The backup folders for a 3-shard database named "Books",
for example, can be named:
2023-02-05-16-17.Books$0 for shard 0
2023-02-05-16-17.Books$1 for shard 1
2023-02-05-16-17.Books$2 for shard 2
backs up all the databases hosted by the cluster, by creating a backup
task for each database and executing all tasks at a scheduled time.
- A server-wide backup will create backups for both non-sharded and
- To create a backup for an entire sharded database, the operation will
define and execute a backup task for each shard, behaving as if it was
The backup task that we define here is similar to the task we
would define for a non-sharded database. As part of a sharded
database, however, this task will be re-defined automatically
by the orchestrator for each shard.
var config = new PeriodicBackupConfiguration
LocalSettings = new LocalSettings
FolderPath = @"E:/RavenBackups"
//Azure Backup settings
AzureSettings = new AzureSettings
StorageContainer = "storageContainer",
RemoteFolderName = "remoteFolder",
AccountName = "JohnAccount",
AccountKey = "key"
//Amazon S3 bucket settings
S3Settings = new S3Settings
AwsAccessKey = "your access key here",
AwsSecretKey = "your secret key here",
AwsRegionName = "OPTIONAL",
BucketName = "john-bucket"
// Google Cloud bucket settings
GoogleCloudSettings = new GoogleCloudSettings
BucketName = "your bucket name here",
RemoteFolderName = "remoteFolder",
GoogleCredentialsJson = "your credentials here"
var operation = new UpdatePeriodicBackupOperation(config);
var result = await docStore.Maintenance.SendAsync(operation);
Casting Backup Results
In a sharded database, results are returned by Backup in a
This type is specific to a sharded database, and casting it using a non-sharded type