Backing up Data Catalog

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This article includes procedures for backing up Data Catalog’s Solr™ data and indexes, the Postgres database, the keystore, and optionally, discovery metadata and UI logs.

NoteThese instructions are intended to back up standalone instances of Data Catalog. If you need to back up Data Catalog as a part of your Lumada DataOps Suite installation, see the Administer section in the LDOS documentation.

You should make regular backups of all Data Catalog metadata such that it can be used to restore the catalog to a snapshot in time. To back up Data Catalog metadata, you should regularly back up the following software:

Solr data and indexes.
Postgres database that contains audit information for Data Catalog functions.
Keystore file that contains the encrypted passwords for the current installation.

ImportantBack up the keystore before you perform any upgrade.

The upgrade process generally backs up the keystore, but it is good practice to have a separate backup in case the upgrade is unable to restore the keystore.

Depending on your requirements, you can also back up the following:

Data Catalog discovery metadata
Discovery metadata supports Data Catalog discovery operations and, if not maintained, it can be reproduced as needed. The discovery metadata location is set during Data Catalog installation, and is stored in the ldc.metadata.hdfs.MetadataServiceHdfsPath property in the configuration.json file in the conf directory.
Data Catalog UI logs
Web server logging information may include access attempts. For complete auditing of login attempts, back up the ldc-ui.log files.

Backup process overview

The process to back up Data Catalog includes several steps. As a best practice, perform these steps in the following order:

Before you begin the backup
Make backup locations
Back up the Solr collection (CDH, EMR, HDP)
Back up Postgres
(Optional) Back up discovery metadata
Back up the keystore
Start Data Catalog services

Before you begin

Before you start the backup, perform the following steps:

Procedure

Make sure there are no Data Catalog jobs running.
As the Data Catalog service user, shut down the Data Catalog web service:
```
$ sudo su ldcuser  
$ /opt/ldc/app-server/bin/app-server stop
```

Make backup locations

Before you back up Data Catalog, you need backup locations for which the service user is granted write access. See the following table to make backup locations or to verify the write permissions for existing locations:

Write accessed by	Location	Example
Solr service user	Computer where a Solr instance is running.	/tmp/ldc-backups
Data Catalog service user	Either of the following options: Computer where a Solr instance is running. Computer where Data Catalog is running.	/tmp/ldc-backups
Data Catalog service user	HDFS	/backups/ldc/backup_discovery_metadata/20170901

Back up the Solr collection

These steps are for CDH, EMR, and HDP, and use the Solr APIs for backup. The APIs do not work with CDH versions prior to 5.9.

Optionally, instead of using the steps below, you can choose one of the following methods for backing up Solr data and indexes:

Use third-party backup utilities and storage
Back up the data location as shown in the Solr admin page:
Use NAS for the data
When creating the Data Catalog collection, you can choose local storage rather than HDFS and point the local storage location to the Network-Attached Storage (NAS).

Use the following steps to back up the Solr collection.

NoteReview the previous methods, then choose the applicable command to use from the following options.

Procedure

For CDH, EMR, HDP (local/HDFS storage), run the applicable command for your environment:

For a one shard collection

curl ‘http://solrnode1:8983/solr/wdcollection_shard1_replica1/replication?command=backup&name=wdcollection_shard1_replica1_backup&location=/tmp/wd-backups’

The command above backs up shard1. If you have more than one shard, you must run the same command for all the respective shards.

For a 2-shard collection
Run the following command in addition to the command above. Enter this command as a single line:
```
$ curl ‘http://solrnode1:8983/solr/wdcollection_shard2_replica1/replication?command=backup&name=wdcollection_shard2_replica1_backup&location=/tmp/wd-backups’
```
For example, if your backup location is /tmp/ldc-backups, the command above will create /tmp/ldc-backups/backup_solr_index in the local file system.

If SSL is enabled

Use the following command with a reference to the SSL certificate:

$ curl --cacert /certs/cert1.pem ‘http://solrnode1:8983/solr/wdcollection_shard1_replica1/replication?command=backup&name=wdcollection_shard1_replica1_backup&location=/tmp/wd-backups’

If Kerberos is enabled

Use the following command to activate authentication (the user specified here is not actually used):

$ curl --negotiate -u solradmin ‘http://solrnode1:8983/solr/wdcollection_shard1_replica1/replication?command=backup&name=wdcollection_shard1_replica1_backup&location=/tmp/wd-backups’

If Kerberos and SSL are enabled

Use the following command:

$ curl --negotiate --cacert /certs/cert1.pem -u solradmin ‘http://solrnode1:8983/solr/wdcollection_shard1_replica1/replication?command=backup&name=wdcollection_shard1_replica1_backup&location=/tmp/wd-backups’

If using SolrCloud, backup the ZooKeeper configuration.

Your values may be different for the ZooKeeper port number and the Data Catalog collection name. Use the same path for the backup as in the previous step (/tmp/wd-backups). Name the configuration directory so you can identify it again, such as backup_zk_config.

CDH

$ solrctl --zk localhost:2181/solr instancedir --get wdconfig /tmp/ldc-backups/backup_zk_config

HDP

$ /opt/lucidworks-hdpsearch/solr/server/scripts/cloud-scripts/zkcli.sh -zkhost localhost.localdomain:2181 -cmd downconfig -confname wdconfig -confdir /tmp/wd-backups/backup_zk_config

EMR

$ /opt/solr/server/scripts/cloud-scripts/zkcli.sh -zkhost zkhost:zkport -cmd downconfig -confname wdconfig -confdir /tmp/wd-backups/backup_zk_config

Back up Postgres

Use the following steps to back up Postgres:

Procedure

Log in to the node where Postgres is installed.
```
$ ssh <ssh-user>@<postgres-host> 
```
Navigate to the Postgres backup directory, typically /data/postgres_backups.
Back up Postgres to a file using the pg_dump command, similar to the following:
```
<pg-bkup>$ pgsql/bin/pg_dump -U ldc -f 20190929_postgres.bak -d ldc_db
```
Compress the backed up file:
```
<pg-bkup>$ gzip 20190929_postgres.bak
```
Upgrade the Postgres backup file to an archive store.

Back up discovery metadata

This is an optional task. The discovery metadata location is set during Data Catalog installation, and is stored in the ldc.metadata.hdfs.MetadataServiceHdfsPath property in the conf/configuration.json file.

Use the following steps to back up the discovery metadata.

Procedure

Verify the location of the discovery metadata in ldc/conf/configuration.json, the value of the ldc.metadata.hdfs.large_properties.path property.
Name the discovery metadata directory so you can identify it again, such as backup_hdfs_metadata.
NoteUse the same path for the backup as in the previous steps: /tmp/ldc-backups.
Example:
```
$ hdfs fs -get /user/ldcuser/.ldc_hdfs_metadata/* /tmp/ldc-backups/backup_discovery_metadata
```

Back up the keystore

The Data Catalog keystore stores the necessary passwords used for various component communications in an encrypted format. The keystore is generated at the time of installation and added to the keystore in the LDC Application Server. The LDC Metadata Server and LDC Agent retrieve the secrets key from the Application Server and then save it to their respective keystores.

Each installation creates a unique secret key that is valid and essential for the Data Catalog functions of that installation.

ImportantBack up the keystore before you perform any upgrade. The upgrade process generally backs up the keystore, but it is good practice to have a separate backup in case the upgrade is unable to restore the keystore.

NoteKeystore backup only applies to Version 2019.3 and up.

Use the following steps to back up the keystore:

Procedure

Back up the keystore for the LDC Application Server in this path:
<LDC Install location>/app-server/jetty-distribution-9.4.18.v20190429/ldc-base/etc/keystore
Back up the keystore for the LDC Metadata Server in this path:
<LDC Install location>/metadata-server/conf/keystore
Back up the keystore for the LDC Agent server in this path:
<LDC Install location>/agent/conf/keystore

Next steps

After backing up all the keystores, restart the Data Catalog web service:

$ /opt/ldc/app-server/bin/app-server start

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Backup process overview

Before you begin

Make backup locations

Back up the Solr collection

Back up Postgres

Back up discovery metadata

Back up the keystore