6.7

Table Of Contents
If you turn off the per file I/O scheduling model, your host reverts to a legacy scheduling mechanism. The
legacy scheduling maintains only one I/O queue for each virtual machine and storage device pair. All I/Os
between the virtual machine and its virtual disks are moved into this queue. As a result, I/Os from different
virtual disks might interfere with each other in sharing the bandwidth and affect each other's performance.
Note Do not disable per file scheduling if you have the HPP plug-in and the latency sensitive threshold
parameter configured for high-speed local devices. Disabling per file scheduling might cause
unpredictable behavior.
Procedure
1 Navigate to the host.
2 Click the Configure tab.
3 Under System, click Advanced System Settings.
4 Edit the value of the VMkernel.Boot.isPerFileSchedModelActive parameter.
Option Description
False Disable the per file scheduling mechanism.
True (default) Reenable the per file scheduling mechanism.
5 Reboot the host for the changes to take effect.
Use esxcli Commands to Enable or Disable Per File I/O Scheduling
You can use the esxcli commands to change the I/O scheduling capability. The capability is enabled by
default.
Prerequisites
Install vCLI or deploy the vSphere Management Assistant (vMA) virtual machine. See Getting Started with
vSphere Command-Line Interfaces. For troubleshooting, run esxcli commands in the ESXi Shell.
Procedure
u
To enable or disable per file I/O scheduling, run the following commands:
Option Description
esxcli system settings kernel set
-s isPerFileSchedModelActive -v
FALSE
Disable per file I/O scheduling
esxcli system settings kernel set
-s isPerFileSchedModelActive -v
TRUE
Enable per file I/O scheduling
vSphere Storage
VMware, Inc. 231