Here is a more complete analysis of the disk I/O across all 3 servers.
1. Cloudron Disk I/O graph (server 1, last 6 hours)
[image: 1773182644022-scherm-afbeelding-2026-03-10-om-23.40.17-resized.png]
The graph shows a constant write baseline of ~2.5 MB/s, 24/7. The spike around 20:00 is the scheduled daily backup — completely normal. The total write of 646 GB over 2 days (~323 GB/day) is almost entirely this constant baseline, not user traffic or backups.
2. iotop breakdown (server 1, 1 minute measurement)
Docker MySQL (messageb): 48.62 MB/min (~0.81 MB/s)
Host MySQL: 23.26 MB/min (~0.39 MB/s)
go-carbon: 9.34 MB/min (~0.16 MB/s)
jbd2 (fs journal): 8.44 MB/min (~0.14 MB/s)
systemd-journald: 4.37 MB/min (~0.07 MB/s)
containerd: 2.02 MB/min (~0.03 MB/s)
dockerd: 1.13 MB/min (~0.02 MB/s)
Total: ~97 MB/min (~1.6 MB/s average)
Note: the average of ~1.6 MB/s is consistent with the graph baseline of ~2.5 MB/s when accounting for peaks and the fact that iotop measures a 1-minute window.
3. InnoDB write activity since last MySQL restart (all 3 servers)
Server 1 (uptime 59 min)
Server 2 (uptime ~40h)
Server 3 (uptime ~40h)
Data written
2.13 GB
55.3 GB
63.5 GB
Effective write rate
~0.58 MB/s
~0.38 MB/s
~0.43 MB/s
Rows inserted/s
6.5
8.8
8.6
Rows updated/s
7.0
4.5
4.0
Log writes/s
28.7
23.6
18.0
All three servers show a consistent insert rate of ~6-9 rows/second in the Docker MySQL, matching exactly 1 new Matomo session every 10 seconds (= health check interval).
Conclusion
The Docker MySQL (~0.4-0.8 MB/s) is the largest single contributor, driven primarily by Matomo session inserts. The total observed disk I/O of 2-4 MB/s is the sum of multiple processes, with the constant Matomo session accumulation as the most significant and most easily fixable component.
