6.0.1
Table Of Contents
- vSphere Troubleshooting
- Contents
- About vSphere Troubleshooting
- Updated Information
- Troubleshooting Overview
- Troubleshooting Virtual Machines
- Troubleshooting Fault Tolerant Virtual Machines
- Hardware Virtualization Not Enabled
- Compatible Hosts Not Available for Secondary VM
- Secondary VM on Overcommitted Host Degrades Performance of Primary VM
- Increased Network Latency Observed in FT Virtual Machines
- Some Hosts Are Overloaded with FT Virtual Machines
- Losing Access to FT Metadata Datastore
- Turning On vSphere FT for Powered-On VM Fails
- FT Virtual Machines not Placed or Evacuated by vSphere DRS
- Fault Tolerant Virtual Machine Failovers
- Troubleshooting USB Passthrough Devices
- Recover Orphaned Virtual Machines
- Virtual Machine Does Not Power On After Cloning or Deploying from Template
- Troubleshooting Fault Tolerant Virtual Machines
- Troubleshooting Hosts
- Troubleshooting vSphere HA Host States
- vSphere HA Agent Is in the Agent Unreachable State
- vSphere HA Agent is in the Uninitialized State
- vSphere HA Agent is in the Initialization Error State
- vSphere HA Agent is in the Uninitialization Error State
- vSphere HA Agent is in the Host Failed State
- vSphere HA Agent is in the Network Partitioned State
- vSphere HA Agent is in the Network Isolated State
- Configuration of vSphere HA on Hosts Times Out
- Troubleshooting Auto Deploy
- Auto Deploy TFTP Timeout Error at Boot Time
- Auto Deploy Host Boots with Wrong Configuration
- Host Is Not Redirected to Auto Deploy Server
- Package Warning Message When You Assign an Image Profile to Auto Deploy Host
- Auto Deploy Host with a Built-In USB Flash Drive Does Not Send Coredumps to Local Disk
- Auto Deploy Host Reboots After Five Minutes
- Auto Deploy Host Cannot Contact TFTP Server
- Auto Deploy Host Cannot Retrieve ESXi Image from Auto Deploy Server
- Auto Deploy Host Does Not Get a DHCP Assigned Address
- Auto Deploy Host Does Not Network Boot
- Authentication Token Manipulation Error
- Active Directory Rule Set Error Causes Host Profile Compliance Failure
- Unable to Download VIBs When Using vCenter Server Reverse Proxy
- Troubleshooting vSphere HA Host States
- Troubleshooting vCenter Server and the vSphere Web Client
- Troubleshooting Availability
- Troubleshooting Resource Management
- Troubleshooting Storage DRS
- Storage DRS is Disabled on a Virtual Disk
- Datastore Cannot Enter Maintenance Mode
- Storage DRS Cannot Operate on a Datastore
- Moving Multiple Virtual Machines into a Datastore Cluster Fails
- Storage DRS Generates Fault During Virtual Machine Creation
- Storage DRS is Enabled on a Virtual Machine Deployed from an OVF Template
- Storage DRS Rule Violation Fault Is Displayed Multiple Times
- Storage DRS Rules Not Deleted from Datastore Cluster
- Alternative Storage DRS Placement Recommendations Are Not Generated
- Applying Storage DRS Recommendations Fails
- Troubleshooting Storage I/O Control
- Troubleshooting Storage DRS
- Troubleshooting Storage
- Resolving SAN Storage Display Problems
- Resolving SAN Performance Problems
- Virtual Machines with RDMs Need to Ignore SCSI INQUIRY Cache
- Software iSCSI Adapter Is Enabled When Not Needed
- Failure to Mount NFS Datastores
- VMkernel Log Files Contain SCSI Sense Codes
- Troubleshooting Storage Adapters
- Checking Metadata Consistency with VOMA
- Troubleshooting Flash Devices
- Troubleshooting Virtual Volumes
- Troubleshooting VAIO Filters
- Troubleshooting Networking
- Troubleshooting MAC Address Allocation
- The Conversion to the Enhanced LACP Support Fails
- Unable to Remove a Host from a vSphere Distributed Switch
- Hosts on a vSphere Distributed Switch 5.1 and Later Lose Connectivity to vCenter Server
- Hosts on vSphere Distributed Switch 5.0 and Earlier Lose Connectivity to vCenter Server
- Alarm for Loss of Network Redundancy on a Host
- Virtual Machines Lose Connectivity After Changing the Uplink Failover Order of a Distributed Port Group
- Unable to Add a Physical Adapter to a vSphere Distributed Switch
- Troubleshooting SR-IOV Enabled Workloads
- A Virtual Machine that Runs a VPN Client Causes Denial of Service for Virtual Machines on the Host or Across a vSphere HA Cluster
- Low Throughput for UDP Workloads on Windows Virtual Machines
- Virtual Machines on the Same Distributed Port Group and on Different Hosts Cannot Communicate with Each Other
- Attempt to Power On a Migrated vApp Fails Because the Associated Protocol Profile Is Missing
- Networking Configuration Operation Is Rolled Back and a Host Is Disconnected from vCenter Server
- Troubleshooting Licensing
- Index
Low Throughput for UDP Workloads on Windows Virtual Machines
When a Windows virtual machine in vSphere 5.1 and later transmits large UDP packets, the throughput is
lower than expected or is oscillating even when other traffic is negligible.
Problem
When a Windows virtual machine transmits UDP packets larger than 1024 bytes, you experience lower than
expected or oscillating throughput even when other traffic is negligible. In case of a video streaming server,
video playback pauses.
Cause
For every UDP packet larger than 1024 bytes, the Windows network stack waits for a transmit completion
interrupt before sending the next packet. Unlike for earlier releases, vSphere 5.1 and later releases do not
provide a transparent workaround of the situation.
Solution
n
Increase the threshold in bytes at which Windows changes its behavior for UDP packets by modifying
the registry of the Windows guest OS.
a Locate the HKLM\System\CurrentControlSet\Services\Afd\Parameters registry key.
b Add a value with the name FastSendDatagramThreshold of type DWORD equal to 1500.
For information about fixing this issue in the Windows registry, see
http://support.microsoft.com/kb/235257.
n
Modify the coalescing settings of the virtual machine NIC.
If the Windows virtual machine has a VMXNET3 vNIC adapter, configure one of the following
parameters in the .vmx file of the virtual machine. Use the vSphere Web Client, or directly modify
the .vmx file.
Action Parameter Value
Increase the interrupt rate of the virtual machine to a higher rate than
expected packet rate. For example, if the expected packet rate is 15000
interrupts per second, set the interrupt rate to 16000 interrupts per
second. Set the ethernetX.coalescingScheme parameter to rbc and
the ethernetX.coalescingParams parameter to 16000. The default
interrupt rate is 4000 interrupts per second.
ethernetX.coalescingScheme
ethernetX.coalescingParams
rbc
16000
Disable coalescing for low throughput or latency-sensitive workloads.
For information about configuring low-latency workloads, see Best
Practices for Performance Tuning of Latency-Sensitive Workloads in
vSphere VMs.
ethernetX.coalescingScheme
disabled
Revert to the coalescing algorithm from earlier ESXi releases.
NOTE The ability to revert to the earlier algorithm will not be
available in later vSphere releases.
ethernetX.coalescingScheme
calibrate
X next to ethernet stands for the sequence number of the vNIC in the virtual machine.
For more information about configuring parameters in the .vmx file, see the vSphere Virtual Machine
Administrationdocumentation.
n
Modify ESXi host coalescing settings.
This approach affects all virtual machines and all virtual machine NICs on the host.
You can edit the advanced system settings list for the host in the vSphere Web Client, or by using a
vCLI console command on the host from the ESXi Shell.
Chapter 8 Troubleshooting Networking
VMware, Inc. 91