This article explains how to migrate an Exasol 7.1 database to Exasol 8.
Introduction
Because of the differences in architecture between the Exasol 7 and Exasol 8 platforms, you cannot update a database directly from Exasol 7.1 to Exasol 8. Instead, you must create a full backup of your Exasol 7.1 database and then restore that backup on a new Exasol 8 database.
This article is an overview of all the major steps in the migration procedure with links to detailed instructions for each step.
To avoid excessive downtime during the process and to prevent a risk of data loss, read the instructions in this section and in Update Considerations carefully before you start the migration procedure.
If your database is running Exasol 7.0, you must update to 7.1 before proceeding. For more information, see Update from Exasol 7.0 to Exasol 7.1.
Files in BucketFS (such as UDF scripts and drivers) are not included in the database backup and must be manually copied over to the new database.
Prerequisites
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The database must be running on the latest Exasol 7.1 version. For information about how to update your database, see Update Procedure (Exasol 7.1).
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The nodes where you deploy Exasol 8 must meet all the system requirements for an Exasol 8 installation. For more information, see System Requirements.
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You must have a valid Exasol 8 license.
Exasol 7.1 licenses are not valid in Exasol 8 because of differences in the license format. For information about how to obtain a valid license for Exasol 8, create a support case.
Plan your downtime
Migrating the database to Exasol 8 requires some downtime when the database is not available to users. The downtime begins at the step when you restart the database on a different port before running a level 1 backup (Step 5), and ends when the backup has been successfully restored in Exasol 8.
The total required downtime is mainly determined by how long the backup and restore operations take. A restore operation will usually take approximately the same amount of time as the backup. For example, if the level 0 backup takes 5 hours and the level 1 backup takes 30 minutes, the total downtime will be at least 6 hours.
Example:
| Operation | Time required for operation | System downtime required |
|---|---|---|
| Create level 0 backup | 5 hours | 0 |
|
Create level 1 backup |
30 minutes | 30 minutes |
|
Restore level 0 backup |
5 hours | 5 hours |
|
Restore level 1 backup |
30 minutes | 30 minutes |
| Total downtime required for backup/restore operations | 6 hours | |
When you calculate the total downtime for the migration you should also allow time for additional operations such as stopping and starting the databases, and for reverting to the previous version in case the migration fails. You should also consider factors in your system environment that might affect the operation, such as network capacity.
Migration procedure
The migration procedure consists of the following major steps:
Step 1: Create an empty Exasol 8 database
The first step is to create an Exasol 8 deployment with the same number of active nodes as the existing Exasol 7.1 database. Exasol 8 can be deployed as an application on a Linux system or as a native cloud deployment on AWS.
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To learn how to install Exasol 8 as an application on hardware or on virtual instances, see Installation.
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To learn how to create a native cloud deployment of Exasol 8 on AWS, see Deploy Exasol on AWS.
For more information about deployment alternatives for Exasol 8, see Get Started with Exasol. If you need more help, create a support case.
The Exasol 8 database must have the exact same number of active nodes as the Exasol 7.1 database that was backed up. Otherwise, the migration will fail.
Step 2: Create a level 0 backup of your Exasol 7.1 database
In Exasol 7.1, create a level 0 backup on a remote archive volume that can also be accessed by the Exasol 8 deployment. In the following step you will create a volume in Exasol 8 that points to this source.
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To learn how to start a manual backup in Exasol 7.1, see Manual Backup.
Step 3: Create a remote archive volume in Exasol 8
In Exasol 8, create a remote archive volume that points to the source that contains the Exasol 7.1 backup.
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To learn how to create a remote archive volume in Exasol 8, see Create a remote archive volume.
If the nocompression option is set on the Exasol 7.1 remote archive volume, it must also be set on the Exasol 8 archive volume. If the option is not set on one of the volumes, it must also not be set on the other volume. Otherwise, restoring the backup on the Exasol 8 database will fail.
To check which options are set on the Exasol 7.1 archive volume, go to the EXAStorage page in EXAoperation and select the volume. If nocompression is included in the Options field, you must also set this option when you create the Exasol 8 volume.
Step 4: Transfer files in BucketFS (optional)
Files stored in BucketFS on the Exasol 7.1 database (such as UDF scripts and drivers) are not included in the database backup. To migrate these files you must manually download them and later upload them to BucketFS in the Exasol 8 database when it is up and running.
We recommend that you use BucketFS Client to download and upload files in BucketFS .
Step 5: Restart the Exasol 7.1 database on a different port
To make sure that clients cannot connect to the Exasol 7.1 database during the migration procedure, you must change the connection port of the database. This step requires that you temporarily stop the database.
To minimize system downtime, make sure that the new Exasol 8 database is running and reachable before you continue with the following steps.
The system downtime for the migration begins at this point.
Step 6: Create a level 1 backup of the Exasol 7.1 database
Before you stop the 7.1 database you should do a level 1 (incremental) backup that contains the changes since the level 0 (full) backup was saved.
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Create a level 1 backup of the Exasol 7.1 database on the remote volume that you used for the level 0 backup.
To learn how to start a manual backup in Exasol 7.1, see Manual Backup.
Step 7: Restore the Exasol 7.1 backup on the Exasol 8 database
The final step is to restore the full backup (level 0 + level 1) on the Exasol 8 database. The restore is made from the remote archive volume in Exasol 8 that points to the same source as the Exasol 7.1 remote archive volume.
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To learn how to restore backups on Exasol 8, see Restore Database from Backup.
If the nocompression option is set on the Exasol 7.1 remote archive volume, it must also be set on the Exasol 8 archive volume. If the option is not set on one of the volumes, it must also not be set on the other volume. Otherwise, the restore operation will fail.
When the restore operation has completed, the Exasol 8 database will automatically restart.
The system downtime for the migration ends at this point.
The migration is now complete and your Exasol 8 database should be running with the data from your old Exasol 7.1 database.
Fallback procedure
If the migration is not successful, you can restart the Exasol 7.1 database on the original port to resume operations while you troubleshoot.
Support
If you need help with the migration procedure, reach out to our Support team. To get help, create a support case.
Next steps
- Make sure that you inform all users about any changes in how to connect to the database after the migration to Exasol 8.
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To learn how to administrate Exasol 8, see the Administration (On-Prem) section.
