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.

For more information about diagnostic bundles, see Generating Diagnostic Bundles. For information about how to collect diagnostic partitions for a purple screen fault in ESXi, see the VMware knowledge base article at http://kb.vmware.com/kb/1004128.http://kb.vmware.com/kb/1004128.

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.