Constant background disk IO on instance with 0 enabled apps

[lewisl9029]

Hi Cloudron team,

I have a Cloudron instance running on an Azure VM right now, and was investigating why my storage bills were much higher than expected (and steadily growing), and seem to have found that disk IO may be the culprit.

My instance started with a number of running apps, and was running at a fairly constant 40 write operations per second initially, and as I temporarily stopped apps to investigate, it decreased proportionately, but even with 0 apps running it was still doing an average of 7 write operations per second:

Curious if you're able to reproduce this, and whether you have any ideas on what's causing this constant disk IO, and any tips on how to reduce idle disk activity on Cloudron itself as well as on apps.

Prior to stopping all my apps, I was accruing around $30 per month of storage costs for 30GB of standard Azure SSD storage, when an idle 30 GB ssd should cost only $2.4: https://azure.microsoft.com/en-us/pricing/details/managed-disks/, to give you a sense of the costs involved.

Thanks!

[girish]

So the bill increasing based on IOPS? I had no idea such disk/pricing existed.

As for the disk usage itself, it is hard to know without installing sort of process level monitor. Since you have no apps, one thing you can try is systemctl stop box and see if the disk writes stop? Apart from that there is mysql, nginx and docker. Maybe you can try stopping services one by one and investigate. Also, what is the disk usage of just a vanilla ubuntu or something?

It seems to me that since there is a spike at around 11 maybe it's because some backup is happening at that point? Is there any CPU or network usage in the same time frame? Cloudron isn't really doing much if there are no apps.

[robi]

@lewisl9029 going further, you can set up an empty VM and how many IOs it "uses".

[marcusquinn]

Yeah, we've been heavily stung by Azure's get you in with low prices and charge you for every single other thing on top pricing. Much, much happier with Hetzner now.

[girish]

@marcusquinn Choosing IOPS based billing seems pretty extreme Well, to me anyway. I am not aware of an web application really paying attention to all this. Maybe system software like databases will pay attention and have regression tests for this but never web apps.