Query regarding incremental-lsn option in PXB

MySQL & MariaDB Percona XtraBackup
1

Hi Team,

We have a requirement for full and incremental backups. Currently, we are utilizing the --incremental-lsn option with the last to_lsn value using the xbcloud binary to perform incremental backups. Below is a sample command:

xtrabackup --backup --stream=xbstream --extra-lsndir=/tmp/xtrabackup-lsndir --target-dir=/tmp/xtrabackup --compress --compress-threads=8 --stream=xbstream --parallel=8 --incremental-lsn=xxxxxxxxxx | xbcloud put --storage=google [options]

Now, I have a question:
Suppose I have taken several incremental backups using incremental-lsn. If, while attempting the next incremental backup with the incremental-lsn value (to_lsn of the last incremental backup), the backup node fails due to a hardware OR some other issue, resulting in data loss and necessitating a node rebuild.

In this scenario, would a subsequent incremental backup succeed with the same older value of incremental-lsn from the new node that we have rebuild or would it fail due to data inconsistency?

MySQL Version: 8.0.35
Xtrabackup: 8.0.35

2

Any update here team?

3

Hello @pravata_dash ,

The forums are a voluntary effort from Percona employees. The forums are not a source of immediate assistance. If you need immediate assistance, you can contact us for a support contract.

4

There is no guarantee that LSN X on node1 is the same as LSN Y on node2. The LSN is (in general) a byte-offset of the REDO log. So, no, you would not be able to restart a failed backup on a new node using the LSN of the old node. LSN is not a GTID; it is InnoDB-specific.

5

Thanks a lot @matthewb for the details.