Hi

Thank you for the details. The verified issue as described.

Issue: For PXC Operator When using 5.7 version with innodb_undo_tablespaces option backup restore will fail.

About innodb_undo_tablespaces:

Undo logs are stored in the system tablespace by default but can be stored in one or more undo tablespaces instead. The number of undo tablespaces used by InnoDB is controlled by the innodb_undo_tablespaces option. This option can only be configured when initializing the MySQL instance. It cannot be changed afterward.

Reproducible steps:

Make sure you add following mysql setting in cr.yaml before starting the cluster 1st time, otherwise MySQL will not allow adding this option once it's already started/initialize. 

cr.yaml  (MySQL undo tablespace setting)

Taking backup:

 As we can see undo tablespace showing in the backup.

But after restore pxc failed to start due to a missing undo file.

[ERROR] InnoDB: Unable to open undo tablespace './/undo001'.

Logs:

Restore pod datadir:

xtrabackup command: I think the problem here is backup not using  MySQL configuration in cr.yaml while restore/prepare stage

Yes, I add this setting to the configuration before initializing pxc cluster. The problem occurs in restore. 

Step:

1. initialize the pxc cluster with innodb_undo_tablespaces  set

2. create the pxc-backup cr to backup the cluster

3. cretate the pxc-restore cr to restore the current cluster, the it will fail

Hi

Thank you for the report.

As I can see from log you are using 5.7 version. for this version,

The number of undo tablespaces used by InnoDB is controlled by the innodb_undo_tablespaces option. This option can only be configured when initializing the MySQL instance. It cannot be changed afterward.

Did you add this setting to the configuration before initializing pxc cluster? Adding innodb_undo_tablespaces option after starting PXC cluster will not work, because Undo logs are stored in the system tablespace by default already which can not be changed later.

Let us know the exact steps. mysql configuration details.