Managing Diagnostic Partitions

Your host must have a diagnostic partition (dump partition) to store core dumps for debugging and for use by VMware technical support. See Generating Diagnostic Bundles. The VMware knowledge base article at http://kb.vmware.com/kb/1004128 explains how to collect diagnostic partitions for a purple screen fault in ESXi.

A 100MB diagnostic partition for each host is recommended. If more than one ESX/ESXi host uses the same LUN as the diagnostic partition, that LUN must be zoned so that all the ESX/ESXi host can access it. Each host needs 100MB of space, so the size of the LUN determines how many servers can share it. Each ESX/ESXi host is mapped to a diagnostic slot. VMware recommends at least 16 slots (1600MB) of disk space if servers share a diagnostic partition. You can set up a SAN LUN with FibreChannel or hardware iSCSI. SAN LUNs accessed through a software iSCSI initiator are not supported.

Caution If two hosts that share a diagnostic partition fail and save core dumps to the same slot, the core dumps might be lost. To collect core dump data, reboot a host and extract log files immediately after the host fails. If another host fails before you collect the diagnostic data of the first host, the second host does not save the core dump.

Retrieving Diagnostic Partition Information

The HostDiagnosticSystem managed object allows you to retrieve information in several ways.

■	Retrieve the HostDiagnosticPartition object from the HostDiagnosticSystem.activePartition property to examine the properties of the active partition.

■	Call the HostDiagnosticPartition.QueryAvailablePartition method to retrieve a list of available diagnostic partitions, in order of suitability.

■	Call the HostDiagnosticPartition.QueryPartitionCreateOptions method to retrieve a list of disks with sufficient space to contain a diagnostic partition of the specified type. The choices are returned in order of suitability.

Creating a Diagnostic Partition

Creating a diagnostic partition requires that you find a suitable partition using one of the query methods. You can then retrieve a creation specification, and perform the actual creation.

To create a diagnostic partition

1	Find a suitable partition by calling HostDiagnosticPartition.QueryAvailablePartition or HostDiagnosticPartition.QueryPartitionCreateOptions.

2	Call HostDiagnosticPartition.CreateDiagnosticPartition, passing in a HostDiagnosticPartitionCreateSpec, which includes information about the diagnostic type, id, storage type, and so on.

On success, this method creates the partition and makes the partition the active partition if specified in the active parameter. On failure, the diagnostic partition might exist, but will not be active even if the partition was supposed to be made active.