Server RAM allocation.

[Koldov]

Having trouble with my memory (no it's not just my age)!

 

I have a VM Host (old tower server with 24GB RAM)...

 

The VMs (and memory allocations) are:

 

VM1 = 8GB

VM2 = 4GB

VM3 = 2GB

 

So, that's 14GB and I should have 10GB left... Now the server (HOST) also runs the OS and Hyper-V role (obviously), SQL (Veeam and Paxton Net2) and Sophos.

 

The system runs at 99% allocation, 99% of the time and 1 of the VMs is set to shut down overnight and restart in the morning, but quite often it won't start because there's no memory, and one of the other VMs slows to a crawl (set to 'dynamic' memory allocation).

 

To overcome this I've stopped the VM shutting down overnight and set the memory allocation to 'fixed'. Ultimately I know I'm just going to have to buy some more RAM, just wondered if 10GB not enough...?

 

Or does this sound about right? Most of the time I can look through the Task Manager/Processes and don't see anything sucking up huge amounts of RAM (admittedly Veeam can get to a couple of GB though).

 

What does Server2019 OS use roughly, 6GB?

[3s-gtech]

Having SQL Server running on a Hyper-V host is a really bad idea. It vacuums up RAM - deliberately, for performance reasons. That will fight your HV role. You can limit memory allocation to SQL Server, but really you should not run anything else on the bare metal.

[TheHyperTechie]

I would buy more ram (as you already know) and migrate some of those services on the host to their own VMs. We used to have Paxton, and ESET on its own VM. I take it the SQL is for SIMS? if so, I would definitely migrate this as @3s-gtech mentioned it really eats up the ram and other resources.

 

Having separate VM's would also be beneficial as if your host packed up, you can just mount the backed-up VM's to a new host.

[Koldov]

Yeah, it's a sticky one as we're a small school, minimal server (and server licenses), minimal budget, etc. Same old story...

 

SQL is for Veeam and Paxton, so I'm not sure I can do much about it (needing SQL on the host for Veeam to backup the VMs)... is that not right?

 

EDIT: SIMS is on the large VM

 

EDIT 2: I put Paxton on the host for stability/uptime, purely because it was initially on a VM and the VM failed = doors not working... and I figured the host was a little more bulletproof...

Edited February 5, 2024 by Koldov

[CHiLL]

I agree with @3s-gtech, it's probably SQL eating all your RAM. Ideally, the hypervisor machine should only be doing that and nothing else, with all other requirements being on other VMs. (I'm sure I also read that they shouldn't even be domain joined for security reasons, though that's not related to this post)

 

Yeah, it's a sticky one as we're a small school, minimal server (and server licenses), minimal budget, etc. Same old story...

 

SQL is for Veeam and Paxton, so I'm not sure I can do much about it (needing SQL on the host for Veeam to backup the VMs)... is that not right?

While we use VMware, our VEEAM server is a VM and we have it backing up all our VMs. IIRC, our license doesn't allow us to backup bare metal servers...but we have the free community edition (with SQL Express) installed on another VM to target those bare metal servers or workstations.

Edited February 5, 2024 by CHiLL

[Koldov]

Unfortunately I'm a little limited (licensing) in the amount of VMs I can spin up for individual roles...

 

I know the host shouldn't be running anything else, but once I've got the host, this leaves me 2 x VMs for all the other roles so some are going to have to co-exist... added to that 1 of the VMs is a DC (which again is another one that shouldn't have any other roles) and I'm left with one VM for everything else!

 

Not sure how I could split them up any better than I have?

[Steve21]

As others mentioned it’s probably the SQL but you can just change the settings of it to not take all ram

 

By default it’ll eat whatever it can, even if you stick another 100Gb in, but in the sql server settings you can limit it down to an amount it won’t go above

 

Steve

[CHiLL]

Unfortunately I'm a little limited (licensing) in the amount of VMs I can spin up for individual roles...

 

I know the host shouldn't be running anything else, but once I've got the host, this leaves me 2 x VMs for all the other roles so some are going to have to co-exist... added to that 1 of the VMs is a DC (which again is another one that shouldn't have any other roles) and I'm left with one VM for everything else!

 

Not sure how I could split them up any better than I have?

I don't know how RAM allocation works on Hyper-V, but on VMware, I don't specify how much the hosts uses (or it's already accounted for). So I just set my subsequent VMs to have x amount of RAM available to them.

 

According to Altaro, 2GB is enough for the host OS and the rest to be allocated to VMs:

For a typical Hyper-V host, expect about 2 GB to be necessary just to run Hyper-V and the management operating system. For a high memory host that will serve a high number of virtual machines, it is wise to plan for as much as 4 GB for the system and overhead.

https://www.altaro.com/hyper-v/memory-management-requirement-usage/#:~:text=For%20a%20typical%20Hyper%2DV,for%20the%20system%20and%20overhead.

However, that's not something I can verify.

[Jcx500]

I always leave 8gb+ for hyper-v hosts especially if they have the gui role. Provision less for esx hosts

[Guest Guest]

Having trouble with my memory (no it's not just my age)!

 

I have a VM Host (old tower server with 24GB RAM)...

 

The VMs (and memory allocations) are:

 

VM1 = 8GB

VM2 = 4GB

VM3 = 2GB

 

So, that's 14GB and I should have 10GB left... Now the server (HOST) also runs the OS and Hyper-V role (obviously), SQL (Veeam and Paxton Net2) and Sophos.

 

The system runs at 99% allocation, 99% of the time and 1 of the VMs is set to shut down overnight and restart in the morning, but quite often it won't start because there's no memory, and one of the other VMs slows to a crawl (set to 'dynamic' memory allocation).

 

To overcome this I've stopped the VM shutting down overnight and set the memory allocation to 'fixed'. Ultimately I know I'm just going to have to buy some more RAM, just wondered if 10GB not enough...?

 

Or does this sound about right? Most of the time I can look through the Task Manager/Processes and don't see anything sucking up huge amounts of RAM (admittedly Veeam can get to a couple of GB though).

 

What does Server2019 OS use roughly, 6GB?

 

Pretty sure it’s again the EULA to run anything but HyperV on the host OS

[thimon]

Yeah, it's a sticky one as we're a small school, minimal server (and server licenses), minimal budget, etc. Same old story...

 

SQL is for Veeam and Paxton, so I'm not sure I can do much about it (needing SQL on the host for Veeam to backup the VMs)... is that not right?

 

EDIT: SIMS is on the large VM

 

EDIT 2: I put Paxton on the host for stability/uptime, purely because it was initially on a VM and the VM failed = doors not working... and I figured the host was a little more bulletproof...

 

Put Paxton back as a VM pronto. We’ve been running Paxton as a VM since day one with no issues. 4 cores and 16GB RAM.

[XiJ]

As others have said, the sql will munch through your ram. Limit it to what you can afford, as much as possible

 

I think you need more ram anyway - I’d go for a min 32gb ram, ideally 64gb these days.

 

Given you aren’t running hundreds of VM’s and things I see no reason not to leave the sql stuff in a VM and limit it.

 

As I’m further discovering the Linux world, I’ve read a few times that spare ram is wasted ram !