如何找出正在读取磁盘的进程？

Question

I'm using a GCP VM, from time to time, I lost ssh connection to this VM. After some investigation, I found that during the time I cannot ssh to the VM, the disk IO read is very high, nearly 100MB/s.

I'm pretty sure I'm not running any process that need do disk IO. So I need to find out which process did this.

How can I do it? I checked logs in /var/log, and there's no suspicious logs.

Since I cannot log into the VM when the reading happens, I need some way to put it in background.

Answer 1

You could use something like iotop --only periodically (cron for example) to see what process is consuming IO. You should be able to install iotop via your package manager ( apt , yum , ...). See this link:

https://www.tecmint.com/iotop-monitor-linux-disk-io-activity-per-process/

In case the link above goes down, you can add something like this in the crontab:

* * * * * root iotop -botqqq --iter=3 >> /var/log/iotop

to check IO usage per process every minute (you can change every 5 minutes, every 10 minutes, etc.). Be careful though that you don't fully fill your disk with /var/log/iotop (rotate logs or something else).