Dell EMC VxFlex Ready Node, User Manual

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Note: For most Linux distributions, NOOP is not the default. Different Linux
versions have different default values. For RHEL7 and SLES 11/12, the default
value is deadline, but for older versions, the default is CFQ.
Paravirtual SCSI controller
The Paravirtual SCSI (PVSCSI) controller should be used on guest VMs for high
performance. It is important that users choose the correct PVSCSI controller, because
choosing the wrong controller can adversely affect performance.
Current PVSCSI queue depth default values are 64 for the device and 254 for the
adapter. Users can increase the PVSCSI queue depth to 256 for the device and 1024
for the adapter inside a Windows virtual machine.
Windows virtual machine:
1. From the command line run:
REG ADD HKLM\SYSTEM\CurrentControlSet\services\pvscsi\Parameters
\Device /v DriverParameter /t REG_SZ /d
"RequestRingPages=32,MaxQueueDepth=254"
2. Reboot the virtual machine.
3. Verify the successful creation of a registry entry:
a. Open the registry editor by running the REGEDIT command from the command
line.
b. Browse to
HKLM\SYSTEM\CurrentControlSet\services\pvscsi
\Parameters\Device
.
c. Verify that the DriverParameter key exists with a value of
RequestRingPages=32, MaxQueueDepth=254.
Linux guests:
1. Edit the
vmw_pvscsi.conf
file:
echo "options vmw_pvscsi cmd_per_lun=254 ring_pages=32" > /etc/
modprobe.d/vmw_pvscsi.conf
2. Re-run
vmware-config-tools.pl
:
vmware-config-tools.pl
You can add up to 4 PVSCSI controllers per guest. Allocating different VxFlex OS
volumes to different PVSCSI controllers can help realize the maximum potential of
guest performance.
It is strongly recommended that you review this VMware Knowledge Base article
(article 2053145) so that you can make educated decisions regarding PVSCSI values.
VxFlex OS performance fine-tuning
Dell EMC VxFlex Ready Node AMS User Guide 125