MySQL High persistent disk usage caused by unknown folders
Article ID: 409719
Updated On:
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Issue/Introduction
High persistent disk usage in MySQL typically signals that the database is performing excessive read/write operations to disk, which can degrade performance and even stall critical workloads.
Sometimes, you might notice there are unknown folders stored in the path, /var/vcap/store. That’s a classic operational blind spot—forgotten or orphaned directories quietly consuming disk over time. Here is an example that a folder, pxc-mysql-backup, in the persistent disk.
mysql/0b35-####-f372:~$ ll /var/vcap/store
total 36
drwxr-xr-x 6 root root 4096 Sep 9 03:46 ./
drwxr-xr-x 12 root root 4096 Jul 20 22:42 ../
drwx------ 2 root root 16384 Jun 18 19:48 lost+found/
drwx------ 2 vcap vcap 4096 Sep 8 23:30 mysql_audit_logs/
drwx------ 20 vcap vcap 4096 Sep 7 04:27 pxc-mysql/
drwxr-xr-x 2 root root 4096 Sep 9 03:46 pxc-mysql-backup/
Cause
The data directory used by MySQL database will be /var/vcap/store/pxc-mysql for pxc-release and /var/vcap/store/mysql for cf-mysql-release.
The unknown folder, /var/vcap/store/pxc-mysql-backup/, might be created as temporary files when following this article, How to manually force a MySQL node to rejoin the HA cluster
Resolution
Clean up the temporary files and the disk space will be released.
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