6.7
Table Of Contents
- vSphere Resource Management
- Contents
- About vSphere Resource Management
- Getting Started with Resource Management
- Configuring Resource Allocation Settings
- CPU Virtualization Basics
- Administering CPU Resources
- Memory Virtualization Basics
- Administering Memory Resources
- Persistent Memory
- Configuring Virtual Graphics
- Managing Storage I/O Resources
- Managing Resource Pools
- Creating a DRS Cluster
- Using DRS Clusters to Manage Resources
- Creating a Datastore Cluster
- Initial Placement and Ongoing Balancing
- Storage Migration Recommendations
- Create a Datastore Cluster
- Enable and Disable Storage DRS
- Set the Automation Level for Datastore Clusters
- Setting the Aggressiveness Level for Storage DRS
- Datastore Cluster Requirements
- Adding and Removing Datastores from a Datastore Cluster
- Using Datastore Clusters to Manage Storage Resources
- Using NUMA Systems with ESXi
- Advanced Attributes
- Fault Definitions
- Virtual Machine is Pinned
- Virtual Machine not Compatible with any Host
- VM/VM DRS Rule Violated when Moving to another Host
- Host Incompatible with Virtual Machine
- Host Has Virtual Machine That Violates VM/VM DRS Rules
- Host has Insufficient Capacity for Virtual Machine
- Host in Incorrect State
- Host Has Insufficient Number of Physical CPUs for Virtual Machine
- Host has Insufficient Capacity for Each Virtual Machine CPU
- The Virtual Machine Is in vMotion
- No Active Host in Cluster
- Insufficient Resources
- Insufficient Resources to Satisfy Configured Failover Level for HA
- No Compatible Hard Affinity Host
- No Compatible Soft Affinity Host
- Soft Rule Violation Correction Disallowed
- Soft Rule Violation Correction Impact
- DRS Troubleshooting Information
- Cluster Problems
- Load Imbalance on Cluster
- Cluster is Yellow
- Cluster is Red Because of Inconsistent Resource Pool
- Cluster Is Red Because Failover Capacity Is Violated
- No Hosts are Powered Off When Total Cluster Load is Low
- Hosts Are Powered-off When Total Cluster Load Is High
- DRS Seldom or Never Performs vMotion Migrations
- Host Problems
- DRS Recommends Host Be Powered on to Increase Capacity When Total Cluster Load Is Low
- Total Cluster Load Is High
- Total Cluster Load Is Low
- DRS Does Not Evacuate a Host Requested to Enter Maintenance or Standby Mode
- DRS Does Not Move Any Virtual Machines onto a Host
- DRS Does Not Move Any Virtual Machines from a Host
- Virtual Machine Problems
- Cluster Problems
Hyperthreading
Hyperthreading technology allows a single physical processor core to behave like two logical processors.
The processor can run two independent applications at the same time. To avoid confusion between
logical and physical processors, Intel refers to a physical processor as a socket, and the discussion in this
chapter uses that terminology as well.
Intel Corporation developed hyperthreading technology to enhance the performance of its Pentium IV and
Xeon processor lines. Hyperthreading technology allows a single processor core to execute two
independent threads simultaneously.
While hyperthreading does not double the performance of a system, it can increase performance by
better utilizing idle resources leading to greater throughput for certain important workload types. An
application running on one logical processor of a busy core can expect slightly more than half of the
throughput that it obtains while running alone on a non-hyperthreaded processor. Hyperthreading
performance improvements are highly application-dependent, and some applications might see
performance degradation with hyperthreading because many processor resources (such as the cache)
are shared between logical processors.
Note On processors with Intel Hyper-Threading technology, each core can have two logical processors
which share most of the core's resources, such as memory caches and functional units. Such logical
processors are usually called threads.
Many processors do not support hyperthreading and as a result have only one thread per core. For such
processors, the number of cores also matches the number of logical processors. The following
processors support hyperthreading and have two threads per core.
n
Processors based on the Intel Xeon 5500 processor microarchitecture.
n
Intel Pentium 4 (HT-enabled)
n
Intel Pentium EE 840 (HT-enabled)
Hyperthreading and ESXi Hosts
A host that is enabled for hyperthreading should behave similarly to a host without hyperthreading. You
might need to consider certain factors if you enable hyperthreading, however.
ESXi hosts manage processor time intelligently to guarantee that load is spread smoothly across
processor cores in the system. Logical processors on the same core have consecutive CPU numbers, so
that CPUs 0 and 1 are on the first core together, CPUs 2 and 3 are on the second core, and so on. Virtual
machines are preferentially scheduled on two different cores rather than on two logical processors on the
same core.
vSphere Resource Management
VMware, Inc. 22