we have 2 Hypervisor called kvm01 and kvm02, both with UCS 4.2-1 errata 52.
kvm01 is DC in an internal kvm domain and kvm02 slave.
We use lvm's for the virtual hard disks, and attach them 'raw' to the VM.
Our main problem is, that we have I/O Delays over 5 even there's no great activity on the Server,
for example compared with an proxmox host,
Univention KVM, I/O about 10MB/s Read/Write -> I/O Delay over 6
Proxmox KVM, I/O about 50 to 80 MB/s R/W -> I/O Delay doesn't even hit 1, mostly about 0,1 - 0,2.
Hardware (Proxmox & UCS) is nearly the same.
2x Intel Xeon E5-2643 v4 @3,4GHz (HT enabled)
192 GB Ram
Storage: Eternus DX80 with SAS Hard drives and two 10GBit fibre connection (multipath & iscsi)
For now we activated writeback cache mode for all VM's, the I/O Delays become minimal better, but are still too high.
Normal I/O Delays should be 1/n where n is the Number of CPU Cores, right?
i already spent hours to find the bottleneck.
the only thing, what could be a problem is the number of vm's and even more the number of cpu cores assigned to the vm's.
There are 10 VM's and 26 & 28 assigned CPU Cores on the kvm hosts.