How to inspect a high Total Disk Read?

One of my LXC has very high TOTAL DISK READ, while Total Disk Write is normal. This LXC has 9 TB Total Disk Read while other VPS only several GB.

How to know which process doing this high disk write? I'm using latest Proxmox 5.3-5.

Running on host

Code:
iotop

should do the job.