Question

Managed DB Disk Usage

Posted on August 2, 2023
DigitalOcean Managed MySQL Database
Asked by Kalev B

Recently one of my managed DBs started alerting me to the disk usage approaching its limit. This baffled me as there wasn’t that much data in the databases. I ran a query on the database to find out the size of the tables and indexes and it totalled 35GB, most of which was in a few storage database and this value seemed accurate.

However I looked at the managed DB settings in DO and it said that it was a 60GB disk. Then I logged into the DO dashboard and the managed DB said it was at 73% disk usage.

Now it’s been a few years since I was at school but I’m fairly sure that 35/60 is not 73%.

I’m miffed as to where the rest of this usage is.

I’m more than happy to pay for more disk space, but when 25GB on a 60GB disk seems to have disappeared, I’m want to understand why before purchase more.

Can anyone offer any tips?

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Bobby Iliev

Site Moderator

• August 3, 2023

Accepted Answer

Hi there,

Indeed you are correct, 35 is approximately 60% of 60, eg: (35 / 60) * 100 = 58.33%.

The difference that you’re seeing could be due to several factors like the MySQL logs and temporary files and binary log files along with InnoDB storage overhead.

If you are interested, you could use some of the following queries and try to hunt down the ~10% disk usage difference that you are seeing using some of those queries here:

Check the size of the binary log files. These logs keep a record of changes to the data, which can be used for replication and recovery:

SHOW BINARY LOGS;

As the managed MySQL database clusters are using InnoDB, it’s possible some space is being taken by data fragmentation and the InnoDB storage format. InnoDB tables also have a storage overhead for maintaining row metadata and index data.

SHOW VARIABLES LIKE 'innodb_buffer_pool_size';

The MySQL services can also reserve some disk space for temporary files, log files slow query logs and query log statistics, and other operational data.

Most likely if you combine the total usage of all of the above it will even out to the mismatch that you are seeing.

Hope that this helps!

Bobby Iliev

Site Moderator

• October 3, 2023

Hi there,

In addition to what has already been mentioned here, you can now add scalable storage to managed database clusters as shown in this video here: