I have a azure student subscription account. From their FAQ page, I understand that I can run two VM without cost, one windows server VM, and one Linux VM.
750 hours of Azure B1S General Purpose Virtual Machines for Microsoft Windows Server 12 months
750 hours of Azure B1S General Purpose Virtual Machines for Linux 12 months
https://azure.microsoft.com/en-us/free/free-account-students-faq/
But, when I ran these two VMs for a week, I have been charged for 10 dollars.
Then I noticed that I am using P10 and P4 Disks. Went back to the faq page, I found that only P6 SSD is free, and I can use two of them.
128 GB of Managed Disks as a combination of two 64 GB (P6) SSD storage, plus 1 GB snapshot and 2 million I/O operations 12 months
What P6 SSD mean? It means SSD with size 64G.
Went back to my Azure portal, I can see that I didn’t spend a penny on the P6 disk.
So, to save money, I resize the disk size with 64G SSD instead. (You cannot change the default vm disk size when creating VM)
For windows, I have to recreate the VM using [smalldisk] windows server 2008 image. Note that, the smalldisk VM comes with 30G disk, I need to shutdown the vm and resize to 64G disk to avoid cost. Yes, the smaller disk (P4) is not free, only P6 is free.
Now I can run both of my VM 24 hours 7 days.
Be very careful when you create new free resource on Azure, make sure they are exactly match the free product described on the faq page.