Hot Backup Examples

How to create a consistent snapshot with the arangobackup tool

Create

Hot backups are created near instantaneously. The single server as well as other deployment modes try to obtain a global write transaction lock to enforce consistency across all servers, databases, collections etc. Hot backups still require no Data Definition operations (e.g., create database, create collection) to be active at the time of hot backup, please review the requirements and limitations for more details.

Once that lock could be acquired the hot backup itself is most readily described as a consistent snapshot on the local file system.

arangobackup create --server.endpoint tcp://myserver:8529 --label my-label

The above will create a hot backup with a unique identifier consisting of the UTC time according to the local computer clock output and the specified label and report the success like below.

2019-05-15T13:57:11Z [15213] INFO {backup} Server version: 3.5.1
2019-05-15T14:20:16Z [15397] INFO {backup} Backup succeeded. Generated identifier '2019-05-15T14.20.15Z_my-label'
If the label marker is omitted then a unique identifier string is generated instead.

There are more options for the cluster mode regarding the acquisition of the global write transaction lock:

  • --max-wait-for-lock: configures how long the system tries to get the global write transaction lock before it reports failure. Its value must be a number in seconds (default: 120 seconds).
  • --allow-inconsistent: if set to false (default), the operation is considered to have failed if the maximal waiting time for the lock is exceeded. If set to true, the system will take a potentially non-consistent hot backup when the timeout is exceeded.
  • --force: will make arangobackup abort ongoing write transactions in order to more quickly acquire the global write transaction lock. This option should be used with caution, as it will potentially abort valid write transactions, meaning client applications will see errors for otherwise valid operations and queries. The force option currently only aborts Stream Transactions but no JavaScript Transactions.

Restore

Once a hot backup is created, one can use the generated backup id, for example 2019-05-15T14.36.38Z_my-label to restore the entire instance to that “snapshot”.

Keep in mind that such a restore is a global operation and affects all databases in an installation. The restore will roll back all data including in the meantime databases, collections, indexes etc. The DB-Server of a single server instance and all DB-Servers of a cluster will subsequently be restarted.
arangobackup restore --server.username root --identifier 2019-05-15T14.36.38Z_my-label

The output will reflect the restore operation’s success:

2019-05-15T15:24:14Z [16201] INFO {backup} Server version: 3.5.1
2019-05-15T15:24:14Z [16201] INFO {backup} Successfully restored '2019-05-15T14.36.38Z_my-label'

Delete

Hot backups, analogous to virtual machine snapshots, cause additional disk usage. With every hot backup a consistent state in time is frozen. Later changes will then have to hold a difference to older hot backups. Compactions can no longer cover events before the last hot backup. Naturally, one may want to be able to free disk space, once hot backups become obsolete.

arangobackup delete --server.username root --identifier <identifier>

The result of the operation is thus delivered:

2019-05-15T15:34:34Z [16257] INFO {backup} Server version: 3.5.1
2019-05-15T15:34:34Z [16257] INFO {backup} Successfully deleted '2019-05-15T13.57.03Z'

List

One may hold a multitude of hot backups. Those would all be available to restore from. In order to get a listing of such hot backups, one may use the list command.

arangobackup list

The output lists all available hot backups:

2019-05-15T15:28:17Z [16224] INFO {backup} Server version: 3.5.1
2019-05-15T15:28:17Z [16224] INFO {backup} The following backups are available:
2019-05-15T15:28:17Z [16224] INFO {backup}  - 2019-05-15T13.57.11Z_my-label
2019-05-15T15:28:17Z [16224] INFO {backup}  - 2019-05-15T13.57.03Z-other-label

Upload

Hot backups can be uploaded to a remote repository, here is an example which uses the S3 protocol:

arangobackup upload --server.endpoint tcp://myserver:8529 --rclone-config-file /path/to/remote.json --identifier 2019-05-13T07.15.43Z_some-label --remote-path S3://remote-endpoint/remote-directory

The output will look like this:

2019-07-30T08:10:10Z [17184] INFO [06792] {backup} Server version: 3.5.1
2019-07-30T08:10:10Z [17184] INFO [a9597] {backup} Backup initiated, use 
2019-07-30T08:10:10Z [17184] INFO [4c459] {backup}     arangobackup upload --status-id=114
2019-07-30T08:10:10Z [17184] INFO [5cd70] {backup}  to query progress.

This uses a file remote.json in the current directory to configure credentials for the remote site. Here is an example:

{
  "my-s3": {
    "type": "s3",
    "provider": "aws",
    "env_auth": "false",
    "access_key_id": "XXXXXXXXXXXXXXXXXXXX",
    "secret_access_key": "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
    "region": "xx-xxxx-x",
    "acl": "private"
  }
}

This process may take as long as it needs to upload the data from the single server or all of the cluster’s DB-Servers to the remote location. However, the upload will take advantage from previously uploaded hot backups which might contain identical files. Therefore, the functionality is incremental, if regular hot backups are taken and uploaded to the same remote site.

The status of the process may be acquired at any later time.

arangobackup upload --server.endpoint tcp://myserver:8529 --status-id=114

where the number given in the --status-id option is the one which was reported in the original upload command.

The output will look like this:

2019-07-30T08:11:09Z [17465] INFO [06792] {backup} Server version: 3.5.1
2019-07-30T08:11:09Z [17465] INFO [24d75] {backup} SNGL Status: COMPLETED
2019-07-30T08:11:09Z [17465] INFO [68cc8] {backup} Last progress update 2019-07-30T08:10:10Z: 5/5 files done

See rclone Configuration for details about the remote.json file to configure the remote site for rclone for different protocols than S3.

Download

Hot backups can be downloaded from a remote repository like this:

arangobackup download --server.endpoint tcp://myserver:8529 --rclone-config-file /path/to/remote.json --identifier 2019-05-13T07.15.43Z_some-label --remote-path S3://remote-endpoint/remote-directory

The output will look like this:

2019-07-30T08:14:43Z [17621] INFO [06792] {backup} Server version: 3.5.1
2019-07-30T08:14:43Z [17621] INFO [a9597] {backup} Backup initiated, use 
2019-07-30T08:14:43Z [17621] INFO [4c459] {backup}     arangobackup download --status-id=250
2019-07-30T08:14:43Z [17621] INFO [5cd70] {backup}  to query progress.

This process may take as long as it needs to download the data to the single server or all of the cluster’s DB-Servers from the remote endpoint given network limitations. However, the download will take advantage from other hot backups which might already or still be present locally that contain identical files. Therefore, the functionality is incremental, if a hot backup is downloaded and a similar one is already present.

The status of the download process may be acquired at any later time.

arangobackup download --server.endpoint tcp://myserver:8529 --status-id=250

The output will look like this:

2019-07-30T08:18:07Z [17753] INFO [06792] {backup} Server version: 3.5.1
2019-07-30T08:18:07Z [17753] INFO [24d75] {backup} SNGL Status: COMPLETED
2019-07-30T08:18:07Z [17753] INFO [68cc8] {backup} Last progress update 2019-07-30T08:14:43Z: 5/5 files done

Rclone Configuration

Rclone  is a versatile open-source remote file sync program that can deal with over 30 different remote file IO protocols. Enterprise Editions of ArangoDB come with a bundled version of rclone, which is distributed under the MIT license. It is used to both download and upload hot backup sets to and from local and cloud operated storage resources.

Hot backup directories, which are subject to an ongoing download cannot be used for restores until the download has finished.

To configure rclone, use the rclone-config-file startup option to point arangobackup to a JSON configuration file. The expected format is an object with user-chosen remote names as attribute keys, and the actual configuration as attribute value (a nested object). The option names and values in the rclone documentation  directly translate into attribute/value pairs in the JSON file. Note that "true" and "false" must be enclosed by double quotes.

{
  "my-remote": {
    "option": "value",
    "boolean": "true"
  }
}

The remote path can be specified via the remote-path startup option. The syntax for remote paths is remote:path, where remote is the name of a top-level attribute in the configuration file, path is a remote path, and both are separated by a colon (e.g. my-remote:/a/b/c).

Some cloud vendors require rclone configuration parameters, which are very specific. It is helpful to download a standalone version of rclone and try to upload and download files to verify that one has a working configuration for the cloud storage in question. The exhaustive documentation parameters of S3 for example are found at rclone.org/s3/ . Every parameter can be executed as an option to the program invocation, say --s3-upload-cutoff=0, as an environment variable like export RCLONE_S3_UPLOAD_CUTOFF=0, or most importantly, for use with ArangoDB, as a key value pair for the JSON files below, { ..., "upload_cutoff": 0, ... }.

S3 

… --rclone-config-file ~/my-s3.json --remote-path my-s3://remote-endpoint/remote-directory

The file my-s3.json could look like this:

{
  "my-s3": {
    "type": "s3",
    "provider": "aws",
    "env_auth": "false",
    "access_key_id": "XXXXXXXXXXXXXXXXXXXX",
    "secret_access_key": "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
    "region": "xx-xxxx-x",
    "acl": "private"
  }
}

More examples and details for S3 configurations can be found at rclone.org/s3/ .

Locally mounted local or remote volumes 

… --rclone-config-file ~/my-local.json --remote-path my-local://mnt/backup/arangodb

The file my-local.json could look like this:

{
  "my-local": {
    "type": "local",
    "copy-links": "false",
    "links": "false",
    "one_file_system": "false"
  }
}

More examples and details for local configurations can be found at rclone.org/local/ .

WebDAV 

… --rclone-config-file ~/my-dav.json --remote-path my-dav://remote-endpoint/remote-directory

This file my-dav.json could look like this:

{
  "my-dav": {
    "pass": "A0OeLviBmwqKyCi7S6Rnn6dG576cJeRN1Nh0Dm5h8k0",
    "type": "webdav",
    "url": "https://dav.myserver.com",
    "user": "davuser",
    "vendor": "other"
  }
}

More examples and details on WebDAV configurations can be found rclone.org/webdav/ .

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