Restore (Galera Cluster) does not delete Databases after restore

[che]

Hello All

We’re using XtraBackup to backup our Galera Cluster. We had some testings. We also tested the restore. We’re doing at 00:30 every day a full backup and then incremental ones. It was working perfectly with prepare and then the restore. But after the restore we see a lot (amount of incremental backups) databases on the restored cluster/server (#mysql50#Incremental-09022018_xxxxx [xxxx = time]). All of those does not have any tables and are 0.0 bytes big. when I want to delete them it says me ‘Error Code: 1010. Error dropping database (can’t rmdir ‘./Incremental-09022018_011001/’, errno: 17)’

What are does databases and how i can delete them? and why are they there?
When i do a ‘dir -l’ on ‘/var/lib/mysql’ i see those databases too, and all belongs to mysql:mysql like the other (normal) databases

Thank you.

[che]

No one? bump

[lorraine.pocklington]

Hi there, sorry for the delay, I just asked the team to take a look at your question…
Are you putting the incremental backups into a subdirectory of the full backup directory?
The problem with that is that MySQL treats every subdirectory as a separate database.
If you see here https://www.percona.com/doc/percona-xtrabackup/2.4/backup_scenarios/incremental_backup.html you will see the full backup is in /base and the incrementals at the same directory level /inc1 /inc2 etc

/data/backups/base /data/backups/inc1 /data/backups/inc2

If that’s not the case, let us know and we can take another view? We would probably need a bit more information from you though in that case about what your set up looks like.

[che]

Hello Lorraine

Sorry for my delay now No Problem.

Yes, i but every incremental backup into a sub of the full backup.
How can i remove those “ghost” Databases?

Thank you.

[lorraine.pocklington]

Hello Che

OK I have checked this for you.

You should be able to just remove these directories with rm - they are not recognised by the data dictionary as databases, but they are being shown as databases because they are in the file system structure. Once the sub-directories are gone, they will no longer be listed by show databases command

If you want to make sure that this is the case - and it would be good practice to do this anyway I think, to verify the suggestion - you could mv one initially and make sure that you are happy that the database is not longer displayed and there is no adverse effect.

[che]

Thank you. It was working - just removed them with rm. To be safe for a week or so (because some times, issues are coming later ;)) i’ve just moved them away to a temporary folder inside a folder at the homedrive.

But, yes, just delete/move them is working.
Thank you!

[lorraine.pocklington]

Thank you, Che,for letting me know, I will pass that back to the team that helped me with the answer.
It is always best to check out rather than experiment and I totally agree with you - ‘safe’ is ALWAYS better than ‘sorry’ - especially in DBA work in my opinion!