Slow performance on VM's, IO Delay

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isaacgross1

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May 4, 2024
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I have a cluster of 3 PVE servers. 1, being my primary, I don't see any issues with, performance is good for the most part. It's just an HP Elitedesk running with an SSD. The other 2 servers however are Dell R420's with HDD spinning disk. I have horrible performance from machines running on these two servers, like web pages taking 15-20 seconds to start loading. The noVNC console in Proxmox it super laggy and takes several seconds to start moving the mouse. I don't have any explanation for why this would be the case running on a way more powerful machine than my primary server other than it's using a spinning disk versus SSD. Would this seriously cause that much loss of performance and IO delay?

PVE1 with no IO delay and good performance.
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PVE2 with horrible performance and around 4% constant IO delay.
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I'm not an expert by any means, but I had similar issues trying to run spinning disks in my Proxmox servers. They seem to work fine for data drives in VMs (IE: our SMB Share drive uses a 6 TB spinning drive for storage), but using them in a VM as a boot drive was just super laggy and slow. I gave up and added SSDs and it was much better. If I recall, I believe I even used SATA SSDs on a few of the servers.
 
Spinning rust is slow and has really bad random IO performance.

This is to be expected.

Replace the harddrives with some used enterprise SSDs.
 
I use spinning disks for some data drives also or just light duty container applications and seems to be fine. But using them as the Proxmox OS drive itself and running the VM's on top also probably isn't the best move. I will definitely try to get some SATA SSD's as I don't have the option for NVME in these servers.
 
isaacgross1 said:
But using them as the Proxmox OS drive itself and running the VM's on top also probably isn't the best move.
Click to expand...
Proxmox installation is fine on HDD(s) as it writes a lot but does not need much read performance.
For VMs, you want SSDs for the much higher IOPS. Never use drives with QLC flash memory and if you can use (enterprise) drives with PLP.
isaacgross1 said:
I will definitely try to get some SATA SSD's as I don't have the option for NVME in these servers.
Click to expand...
Go for enterprise (SATA) SSDs with PLP if you can. The endurance and sync write performance will be much better (even if it is SATA).
 
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