I have a Windows server 2012 R2 Host PC. There is a Windows 10 Hyper V instance running in it. This Hyper V instance has 2 HDD's and 1 SSD , all 3 connected directly to the VM by creating an SCSCI controller and selecting the drives.
HDD 1: Seagate Exos 7E2 Enterprise internal 1TB SATA ST1000NM0008
HDD 2: Seagate Constellation ES.3-ST1000NM0033
SSD: Kingston 120GB UV400 SSD
Data transfer speed between two HDD’s attached to this Hyper V instance is 180MB/s. Data Transfer from the SSD to any one of the HDD is initially 400MB/s or above, after 30-35% transfer speed is 170-180MB/s.
But transfer speed from any one of the HDD to SSD, is initially 200MB/s. After transfer completion of 40-50% the transfer speed drops down to 30-40MB/s or lower. When all 3 (2 HDD's and 1 SSD) is allocated and used in Host PC (VM is off), transfer from any of the HDD to SSD is in the range of 250-300 MB/s constant without any drop in transfer speeds.
What I have tried:
I have updated Windows Server 2012 R2 Host PC to the latest version available (KB5018474) but the SSD problem was not solved in the Hyper V instance running inside it.
Also tried testing the SSD and HDD in Hyper V instance running in Windows 10 Host (KB5014023) and the results were no different.
I have also mounted these disks to different SCSI controllers as well, but still getting the same transfer speed when copying files from HDD to SSD.
The problem with SSD’s emerging only when it is used in Hyper V (No problem when directly attached to Host PC). Are there any obvious settings in Hyper V that might be causing this problem?
