ESXi does not apply bandwidth and throughput limits when both are configured for a SCSI virtual disk in the configuration file of a virtual machine
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ESXi does not apply bandwidth and throughput limits when both are configured for a SCSI virtual disk in the configuration file of a virtual machine

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Article ID: 344655

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Updated On:

Products

VMware vCenter Server VMware vSphere ESXi

Issue/Introduction

  • Both bandwidth and throughput limits of a SCSI virtual disk are configured by using parameters in the virtual machine configuration file .vmx. For example, the configuration file might contain these limits for a scsi0:0 virtual disk:

    sched.scsi0:0.throughputCap = 80IOPS
    sched.scsi0:0.bandwidthCap = 10MBps
    sched.scsi0:0.shares = normal
  • The configured bandwidth and throughput caps are violated.


Environment

VMware vSphere ESXi 5.1
VMware vCenter Server 5.1.x
VMware vSphere ESXi 5.0
VMware vCenter Server 6.0.x
VMware vCenter Server 5.0.x
VMware vSphere ESXi 6.0
VMware vCenter Server 5.5.x
VMware vSphere ESXi 5.5

Resolution

This is a known issue affecting ESXi 5.5 and 6.0.

This issue is resolved in ESXi 5.1 Update 2. For more information, see VMware ESXi 5.1 Update 2 Release Notes available at VMware Downloads.

Currently, no resolution exists for ESXi 5.5 or 6.0.

To work around the issue, follow these steps.
To have the configured bandwidth and throughput limits of the SCSI virtual disk work as intended when applied together, revert the disk I/O scheduler to an earlier version by using the vSphere Web Client or the esxcli system settings advanced set command.

Revert the disk I/O scheduler to an earlier version by using the vSphere Web Client

In the vSphere Web Client, edit the Disk.SchedulerWithReservation parameter in the Advanced System Settings list for the host.

  1. Navigate to the host.
  2. On the Manage tab, click Settings and click Advanced System Settings.
  3. Locate the Disk.SchedulerWithReservation parameter.

    Note: You can use the Filter or Find text boxes to find the parameter easily.

  4. Click Edit and set the parameter to 0.
  5. Click OK.

Revert the disk I/O scheduler to an earlier version by using an ESXCLI command

In the ESXi Shell to the host, run this console command:

esxcli system settings advanced set -o /Disk/SchedulerWithReservation -i=0
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