GitHub user akrasnov-drv closed a discussion: VM Disk performance issue

Hi,
We see degraded performance in our VMs in CloudStack (4.20.0.0) during 
compilation and other heavy I/O operations.
I set our compute offerings to use local disk, nevertheless when there are 
20-40 VMs per host, it does not work well.
As I understand it happens because of shared base disk architecture used by 
CloudStack with QCOW images.

According to information I found for QCOW:
Case-Based Limits:
        •       Light workloads: 10-20 images sharing one base can work fine.
        •       Heavy workloads (e.g., database, high IOPS): Keep it below 5 
per base.
        •       Cloud setups (OpenStack, CloudStack): Optimized storage 
backends (Ceph, LVM) are preferable.

Please advise if
- there is a way to limit number of images per shared base (or completely 
change this to independent disks)
- there is a way to define compute offering initially with 2 disks - 1st root 
with shared base from template, 2nd independent and empty.

Thanks,
Alex. 

GitHub link: https://github.com/apache/cloudstack/discussions/10468

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