Performance of a volume inside container

General
1

Hello,

I am new to Docker. I could not find details about performance of volume inside container.
I saw a strange behavior in Amazon AWS EC2 instance.

We used Gen purpose and Provisioned volumes.

Using IOzone tool

I got following performance metrics for the General purpose volume.

Machine is same. IOZone command was executed for the same volume inside and outside container.

Strangely, for some operations , the volume inside docker container performed better than the same volume outside container. For example

Random Write (Small block size - 8K):
Vol outside container: 2.2G/S
Vol inside container: 2.96G/S

Read (Mid block size - 64K):
Vol outside container: 9 G/S
Vol inside container: 10.2 G/S

Random Read (Small block size - 8K):
Vol outside container: 5.2 G/S
Vol inside container: 7.5 G/S

Random Read (Mid block size - 64K):
Vol outside container: 8.5 G/S
Vol inside container: 9.8 G/S

In other operation Volume outside container performed better or equal as expected.

Can some one explain, why Volume inside docker performed better for these operations ?

Thanks
K