I have installed ESXi 6.5 on IBM x3650M4 (Raid5, 8x300Gb on ServeRAID M5110e controller). The raid performance is very low (it drops to 6-7Mb / sec). Local copying of files on partitions of virtual machines takes a very long time.
On this physical server I made a test - I removed the ESX system and installed Windows 2008 R2. Raid on this system works very efficiently (250-300Mb / sec).
as part of tests on this IBM X3650M4, I installed ESX 6.7.0 Update 2 (Build 13981272), created a new virtual machine (win2008r2), I installed vmtools. The test of copying large files on partitions was very bad again. Transfer quickly drops to 5-10mb / sec.
All operations related to this server under the ESX6.5 system are very slow (recovering virtual machines using Veeam, copying / moving virtual machines to this server, copying files between virtual machines on this ESX, etc.)
The controller has uploaded the latest available firmware.
Where can the problem be that the server disk performance under the ESX system is so low?