How to calculate a physical server according to the parameters of virtual machines?

Question

System administration

Good day.
Now there are a number of VMs in rach clouds. We thought about our server. And the question arose how to choose the configuration.
Now a total of 12 VMs use 53 RAM, 27CPU, 600 HDD.

What size physical server will cover the current resources?

Answer 1

Now a total of 12 VMs use 53 RAM, 27CPU, 600 HDD.

53 RAM - well, everything is clear here, put 64GB of RAM, and that's enough.
27CPU - and what does it say, and what does it mean? In fact, they are different CPUs, both in speed and performance. The 3.5GHz Xeon is not exactly the same as the 1.2GHz Celeron.
In virtual machines, CPU cores are usually allocated. And it's not always guaranteed.
600 HDD - here the number of HDDs does not carry any information at all. You need to know the required amount of storage, and the requirements for speed, and I / O operations, and what latency is considered acceptable. In general, how many gigabytes and IOPS do you need? Unclear.

What size physical server will cover the current resources?

Are you in meters? Width, height, and depth? Or in units?

Answer 2

The one that will have 53 RAM, 27CPU, 600 HDD.

Answer 3

64 GB of RAM minimum, better to 90.
32 cores.
4 terabyte array.

Answer 4

Keep in mind that in the cloud your tasks are probably solved by a group of different servers + storage systems. If your data and VM availability are important to you, stay away from the swamps - think about the fact that you will need to replicate the entire provider infrastructure.
One server means that stopping it is a scam for everything, which means that redundancy is needed, preferably according to the 2n + 1 scheme. Since there are several servers, you will have to somehow share the storage between them - this is either buying a disk shelf, or another server for a SAN like ceph or similar.
It needs to be switched somehow - you need switches, 10G network cards, cables, and so on.
It is necessary to supply electricity - uninterruptible power supplies and cool - air conditioners.
As a result, your loads run into something like this one piece of hardware for 20-50, depending on the wishes (suddenly you want an SSD) + two full-stack admins at 150-250 k per month.
A BLADE-box like Supermicro is well suited for this case, put three blades in it, a pair of 10G switches, two NVMEs in each blade - SSD for 2-4T, 128G RAM and CEPH. It will turn out an indestructible and fast system with a good reserve for expansion.