VMware vSphere: comparison of Paravirtual and LSI SCSI adapters

You may know that VMware vSphere offers several types of SCSI adapters for virtual machines depending on the OS. The main types are "LSI Logic SAS" and "VMware Paravirtual". There are a lot of articles on this topic (e.g. https://blogs.vmware.com/vsphere/2014/02/vscsi-controller-choose-performance.html). But the real comparison of the performance I saw once, but it's a bit outdated (ESXi 5.0 and Windows Server 2008R2).

Therefore, I did my tests (although not on the latest versions of OS) and compare IOPS, Latency and CPU usage. As a load generator used IO meter 1.1.0.

Test stand

• Hypervisor
• ESXi - 6.0 4192238
• Disk - Samsung EVO 850 128 GB, SATA 3
• Datastore - VMFS 5.61, SSD, 1 MB block
• Virtual Machine
• 1 vCPU 2,3 GHz
• Windows Server 2012 R2
• Disk - 80 GB Thin, NTFS

Results

Block	4 KB	8 KB	16 KB	32 KB	64 KB	128 KB	256 KB
Total IOPS
VMware Paravirtual	19571	15942,10	11474,91	7150,80	4376,5	2453,13	1401,93
LSA Logic SAS	19047	15814,60	11475,70	7152,35	4194	2441,00	1376
Average IO Response time, ms
VMware Paravirtual	0,1	0,12	0,17	0,27	0,45	0,82	1,43
LSA Logic SAS	0,1	0,12	0,17	0,27	0,47	0,81	1,45
CPU utilization, %
VMware Paravirtual	28,20	26,14	18,81	12,92	8,14	6,04	4,80
LSA Logic SAS	38,24	30,40	23,12	15,66	10,25	6,71	5,05

Graphs

Conclusions

VMware Paravirtual SCSI adapter faster LSI on about 2% (0 - 3%), but CPU load less on about 17% (10 - 26%). My advice - use Paravirtual where is it possible (Compatibility Guide).