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Proxmox - High IO (slow VMs) on SyS/OVH machines




Posted by Terrum, 11-24-2016, 03:04 PM
(Machine I am using: https://www.soyoustart.com/en/offers/e5-sat-1-32.xml ) I recently migrated to Proxmox after some issues with a previous hypervisor, however with SyS/OVH's default installation settings, it appears the IO can get very high (from 15-20%+ when cloning a disk and, according to a client, they can feel the VM's performance degrade greatly when doing something as simple as downloading a file on the VM). I was looking through this thread https://forum.proxmox.com/threads/ve...-server.10804/ and I wasn't sure whether the VHDs I use need to have read/write cache enabled on them? Or whether it's the physical disks that need to have read/write cache enabled on them. On the VHDs I use 'Default (No Cache)' however on the physical disks they are enabled. I am using SyS/OVH's default RAID 1 settings that come pre-installed with their Proxmox 3.4 installer with no settings changed. Does anyone have a similar experience or any suggestions with what changes they have made related to the disk settings either before or after setup? I hope someone can help that has experience with the SyS automated setup of Proxmox 3.4! Any help would be incredibly appreciated! Many thanks EDIT: It might also be important to add that before the migration (I'm using the exact same machine before the migration as I am now with Proxmox), when using my previous hypervisor, there were no IO issues or slowness issues. Also anything as simple as a single client unpacking a ZIP archive will cause the whole machine to slow down - so it must be a disk issue of sorts (definitely an IO delay seeing as the percentage goes high during this) Last edited by Terrum; 11-24-2016 at 03:12 PM.

Posted by RackRent, 11-24-2016, 03:13 PM
use raid 10. Plus write back cache enable in proxmox for vm. It gains io.

Posted by Terrum, 11-24-2016, 03:19 PM
Thanks a lot RackRent! I'll try them both

Posted by stefeman, 11-24-2016, 06:29 PM
I had this exact same problem. Steps taken: ext4 = much faster than default ext3 nobarrier = makes a huge difference Writeback cache = useful Noatime Nodelatime commit=10 Really improved my IO performance. What panel are you providing for customers if you use proxmox for hosting?

Posted by Terrum, 11-24-2016, 06:37 PM
I'm just using the Proxmox panel for the customers (giving them a username and password to access it through). That's some fantastic steps, I'll definitely consider them too Thank you. Did you use RAID 1 or 10 with those steps? Also with those steps, are you referring to the VHDs or the physical HDD of the machine I need to set those to? Many thanks! Last edited by Terrum; 11-24-2016 at 06:51 PM.

Posted by stefeman, 11-24-2016, 07:24 PM
I refered to the host machine. More specifially to the partition containing storage of VM's I use RAID1 but this is only for myself and 5 of my friends. RAID10 would be ideal but since im on budget, its not option for me to have 4 drives.

Posted by Terrum, 11-24-2016, 07:34 PM
I see, so RAID 10 is out of the equation for me too then seeing as the E5-SAT-1-32 only offers two drives, as well. Not to worry! Write back cache has been enabled on the VHDs (Write caching was already enabled on the machine's HDDs, as proven in the second quote of my OP). What is nodelatime though? I've never heard of that. Do you mean nodiratime? Just checking before I make any changes In the meantime I'll check if nobarrier, noatime and the commit parameters are on the mount or not!



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