[libvirt-users] CPU and Memory requirements for host OS ( CentOS 7.6) on Dell Poweredge R630 server
Hi, I am running Dell R630 Poweredge 1U with 32 cores vCPU's and 96 GB RAM. What should be the minimum numbers of CPU cores and memory that should be reserved for host OS (CentOS 7.6) and the remaining CPU cores and memory resources to be allocated for Guest OS? I look forward to hearing from you and thanks in advance. Best Regards, Kaushal
That depends on what you plan on doing with the host. IIRC live VM migrations use host CPU time, and depending on transport can use quite a bit of CPU (for encryption/compression). Same with storage, if you have a ZFS/btrfs/LVM2/RAID/encryption setup that requires a lot of CPU, that's also counted against host CPU time. libvirtd itself doesn't need all that much resources for itself, that said. 2 cores and 2GB RAM should suffice as baseline? Plus whatever you need to meet above needs, if any apply. On 26.08.19 20:02, Kaushal Shriyan wrote:
Hi,
I am running Dell R630 Poweredge 1U with 32 cores vCPU's and 96 GB RAM. What should be the minimum numbers of CPU cores and memory that should be reserved for host OS (CentOS 7.6) and the remaining CPU cores and memory resources to be allocated for Guest OS?
I look forward to hearing from you and thanks in advance.
Best Regards,
Kaushal
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On Tue, Aug 27, 2019 at 1:05 PM Sven Schwedas <sven.schwedas@tao.at> wrote:
That depends on what you plan on doing with the host. IIRC live VM migrations use host CPU time, and depending on transport can use quite a bit of CPU (for encryption/compression). Same with storage, if you have a ZFS/btrfs/LVM2/RAID/encryption setup that requires a lot of CPU, that's also counted against host CPU time.
libvirtd itself doesn't need all that much resources for itself, that said. 2 cores and 2GB RAM should suffice as baseline? Plus whatever you need to meet above needs, if any apply.
Hi Sven, So for host OS, 2 vCPU's with 2GB Memory is enough. Please comment. I have spawned 10 KVM based VM's with CentOS 7.6 on the bare metal server (Dell R630 Poweredge 1U with 32 cores vCPU's and 96 GB RAM.) Is there a way to find out the system resources utilization for all the 10 VM's? Best Regards,
*may or may not be* enough - a huge amount depends on your workloads. As ever, watching the available memory and how much CPU is in use in "top" will give you a better idea of how your infrastructure is behaving, as will watching the server charts in virt-manager if it's available. For example, for some of our workloads, we can overcommit memory by a factor of two (so run nearly 200G of virtual server RAM on a 96G machine) and overcommit CPU by nearly a factor of three, and everything's fine. For other workloads, they need to get all the resources we promised them. Sorry not to give an exact answer; it's a rather similar situation to "is this machine big enough to run my database server?" but with more variables. - Peter On Tue, 27 Aug 2019 at 17:20, Kaushal Shriyan <kaushalshriyan@gmail.com> wrote:
On Tue, Aug 27, 2019 at 1:05 PM Sven Schwedas <sven.schwedas@tao.at> wrote:
That depends on what you plan on doing with the host. IIRC live VM migrations use host CPU time, and depending on transport can use quite a bit of CPU (for encryption/compression). Same with storage, if you have a ZFS/btrfs/LVM2/RAID/encryption setup that requires a lot of CPU, that's also counted against host CPU time.
libvirtd itself doesn't need all that much resources for itself, that said. 2 cores and 2GB RAM should suffice as baseline? Plus whatever you need to meet above needs, if any apply.
Hi Sven,
So for host OS, 2 vCPU's with 2GB Memory is enough. Please comment. I have spawned 10 KVM based VM's with CentOS 7.6 on the bare metal server (Dell R630 Poweredge 1U with 32 cores vCPU's and 96 GB RAM.) Is there a way to find out the system resources utilization for all the 10 VM's?
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participants (3)
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Kaushal Shriyan -
Peter Crowther -
Sven Schwedas