...using harddisk locally attached to host, and with transfers above 80MBs.
I've tried using an LSI RAID controller 9341i (SAS 3008 chipset), and using newest driver and firmware.
Tried all combination of RAID, non-RAID and setting the VM controller to use VMware paravirtual ....same result.
By the way I got the exact same behaviour using the onboard SATA controller.
When more than 2-3GB are copied in the guest (Windows) the harddisk latency goes crazy and transfers drops to anything between 0 to 30MBs.
It seems like some kind of buffer is filled up.
If I pause the copying a few second and resume, speed is regained for a while and then drops again.
To recreate this problem the transfer has to be no less than about 80MBs otherwise this "buffer", or whatever it is, will not be filled up quickly enough.
This RAID controller doesn't have have any cache memory, but ESX should still not behave like this?
And I'm using SATA disks....it that why? (they have 64MB cache and should be filled up long before reaching 3GB copying).
When using the RAID controller as pass-through I don't get this problem. But then I cannot have my Windows system in an VMDK file, right?.
And I assume I can only use the controller for one VM, right?
Using ESX 6 update 2.
Chipset: Intel C232 and C236 (tried both)
