Poor passthrough disk performance CentOs7 VM on Hyper-V
Posted: 2018/01/23 12:10:48
Hello,
I'm running a CentOS 7 VM on Microsoft Hyper-V Server with the following configuration:
-HOST 4 Intel Xeon E3-1226 v3 CPUs, 8 GB RAM, Gigabyte ethernet, 1 TB RAID 1 (volume1) for VM's VHDX & 4 TB RAID 1 (volume2) as passthrough disk for samba share on VM - physical disks (ST1000DM010 & WD40EFRX) are connected to the SAS backplane on a Fujitsu RAID D2616 (LSISAS2108 chip) controller. Both volumes have the same write policy (write back) as the controller is protected by BBU and the server is on UPS.
-VM 4 vCPUs, 3 GB RAM, Gigabyte ethernet, 32 GB fixed VHDX (sda for OS) & 4 TB passthrough disk (sdb) connected both via SCSI controller
The main purpose of the VM is to serve as a samba share. I've formated the passthrough disk in XFS, mounted in /RAID and shared via smb. On the same VM I have another smb share (for testing only) that resides on the VHDX.
The problem: write performance (~40 Mb/s) on the passthrough disk is far less than the VHDX (~110-120 Mb/s which is nearly the maximum speed of the gigabyte adapter). The IO scheduler on both VM disks is noop - the hypervisor is doing the IO scheduling. I surely know the hardware is capable of grater write speeds.
So far I changed the IO sheduler to deadline and cfq, first only for the passthrough disk, then for both, but nothing changed. Then I changed the write policy on the host to write through, but there wasn't any improvement too.
I am no Linux expert but I've noticed the passthrough disk is using drivers from LSI, though it is presented to the VM through the host's scsi controller.
[0:0:0:0] disk Msft Virtual Disk 1.0 /dev/sda
dir: /sys/bus/scsi/devices/0:0:0:0 [/sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/VMBUS:00/b92f53c8-2d73-4724-ac25-726d87345113/host0/target0:0:0/0:0:0:0]
[1:0:0:0] disk LSI RAID 5/6 SAS 6G 2.12 /dev/sdb
dir: /sys/bus/scsi/devices/1:0:0:0 [/sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/VMBUS:00/7f8c96c8-a2be-476c-951f-bb5ccdac0596/host1/target1:0:0/1:0:0:0]
Maybe the poor performance could be from the linux LSI RAID 5/6 SAS 6G driver?
Could someone please shed some light on this?
Kind regards,
I'm running a CentOS 7 VM on Microsoft Hyper-V Server with the following configuration:
-HOST 4 Intel Xeon E3-1226 v3 CPUs, 8 GB RAM, Gigabyte ethernet, 1 TB RAID 1 (volume1) for VM's VHDX & 4 TB RAID 1 (volume2) as passthrough disk for samba share on VM - physical disks (ST1000DM010 & WD40EFRX) are connected to the SAS backplane on a Fujitsu RAID D2616 (LSISAS2108 chip) controller. Both volumes have the same write policy (write back) as the controller is protected by BBU and the server is on UPS.
-VM 4 vCPUs, 3 GB RAM, Gigabyte ethernet, 32 GB fixed VHDX (sda for OS) & 4 TB passthrough disk (sdb) connected both via SCSI controller
The main purpose of the VM is to serve as a samba share. I've formated the passthrough disk in XFS, mounted in /RAID and shared via smb. On the same VM I have another smb share (for testing only) that resides on the VHDX.
The problem: write performance (~40 Mb/s) on the passthrough disk is far less than the VHDX (~110-120 Mb/s which is nearly the maximum speed of the gigabyte adapter). The IO scheduler on both VM disks is noop - the hypervisor is doing the IO scheduling. I surely know the hardware is capable of grater write speeds.
So far I changed the IO sheduler to deadline and cfq, first only for the passthrough disk, then for both, but nothing changed. Then I changed the write policy on the host to write through, but there wasn't any improvement too.
I am no Linux expert but I've noticed the passthrough disk is using drivers from LSI, though it is presented to the VM through the host's scsi controller.
[0:0:0:0] disk Msft Virtual Disk 1.0 /dev/sda
dir: /sys/bus/scsi/devices/0:0:0:0 [/sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/VMBUS:00/b92f53c8-2d73-4724-ac25-726d87345113/host0/target0:0:0/0:0:0:0]
[1:0:0:0] disk LSI RAID 5/6 SAS 6G 2.12 /dev/sdb
dir: /sys/bus/scsi/devices/1:0:0:0 [/sys/devices/LNXSYSTM:00/device:00/ACPI0004:00/VMBUS:00/7f8c96c8-a2be-476c-951f-bb5ccdac0596/host1/target1:0:0/1:0:0:0]
Maybe the poor performance could be from the linux LSI RAID 5/6 SAS 6G driver?
Could someone please shed some light on this?
Kind regards,