When you set up MSCS on ESXi, see the checklists to configure your environment according to the requirements. You can also use the checklists to verify that your setup meets the requirements if you need technical support.
Requirements for Clustered Disks
Each type of clustered disk has its own requirements, depending on whether it is in a single-host cluster or multihost cluster.
| Component | Single-Host Clustering | Multihost Clustering |
|---|---|---|
Clustered virtual disk (.vmdk) |
SCSI bus sharing mode must be set to virtual. | Not supported. |
| Clustered disks, virtual compatibility mode (non-pass-through RDM) | Device type must be set to virtual compatibility mode. SCSI bus sharing mode must be set to virtual mode. A single, shared RDM mapping file for each clustered disk is required. |
Device type must be set to virtual compatibility mode for cluster across boxes, but not for standby host clustering or cluster across boxes on Windows Sever 2008. SCSI bus sharing mode must be set to physical. Requires a single, shared RDM mapping file for each clustered disk. See VMware knowledge base article http://kb.vmware.com/kb/1016106 to mark the device as perennially reserved on RDM LUNs used for MSCS virtual machines. This configuration is not supported on Windows Server 2008 and higher. This is a valid configuration only on Windows Server 2003. |
| Clustered disks, physical compatibility mode (pass-through RDM) | Not supported. | Device type must be set to Physical compatibility mode during hard disk creation. SCSI bus sharing mode must be set to physical (the default). A single, shared RDM mapping file for each clustered disk is required. |
| Clustered disks, physical compatibility mode (Shared VVol storage) | Not Supported. | SCSI bus sharing mode must be set to physical. |
| All types | All clustered nodes must use the same target ID (on the virtual SCSI adapter) for the same clustered disk. A separate virtual adapter must be used for clustered disks. |
|
Other Requirements and Recommendations
The following table lists the components in your environment that have requirements for options or settings.
| Component | Requirement |
|---|---|
| Disk | If you place the boot disk on a virtual disk, select Thick Provision during disk provisioning. The only disks that you should not create with the Thick Provision option are RDM files (both physical and virtual compatibility mode). |
| Windows | Use:
For Windows Server 2003 SP1 and SP2, use only two cluster nodes. For Windows Server 2008 SP2 and above, you can use up to five cluster nodes. Disk I/O timeout is 60 seconds or more (
Note: If you recreate the cluster, this value might be reset to its default, so you must change it again.
The cluster service must restart automatically on failure (first, second, and subsequent times). |
| ESXi configuration | Do not overcommit memory. Set the Memory Reservation (minimum memory) option to the same as the amount of memory assigned to the virtual machine. If you must overcommit memory, the swap file must be local, not on the SAN. ESXi 5.0 uses a different technique to determine if Raw Device Mapped (RDM) LUNs are used for MSCS cluster devices, by introducing a configuration flag to mark each device as "perennially reserved" that is participating in an MSCS cluster. For ESXi hosts hosting passive MSCS nodes with RDM LUNs, use the esxcli command to mark the device as perennially reserved: esxcli storage core device setconfig -d <naa.id> --perennially-reserved=true. See KB 1016106 for more information. |
| Multipathing | Contact your multipathing software vendor for information and support of non-VMware multipathing software in vSphere. |
Required Information for Technical Support
The following table lists the files and settings to collect if you require technical support. Technical support uses these files and settings to analyze clustering issues.
| File or Information | Description or Location |
|---|---|
| vm-support tarball | Contains the vmkernel log, virtual machine configuration files and logs, and so on. |
| Application and system event logs of all virtual machines with the problem | |
| Cluster log of all virtual machines with the problem | %ClusterLog%, which is usually set to %SystemRoot%\cluster\cluster.log. |
| Disk I/O timeout | HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Disk\TimeOutValue |
| vSphere Client display names and Windows NETBIOS names of the virtual machines experiencing the problem | |
| Date and time that the problem occurred | |
| SAN configuration of the ESXi system | Details about LUNs, paths, and adapters. |
| (Optional) Memory dump of the virtual machine | Required if a guest virtual machine fails (a blue screen appears with an error message). |
