To run successfully, your host must have a diagnostic partition or a dump partition to store core dumps for debugging and technical support. You can create the diagnostic partition on a local disk or on a private or shared SAN LUN.

A diagnostic partition cannot be located on an iSCSI LUN accessed through a software iSCSI initiator.

Each host must have a diagnostic partition of 100MB. If multiple hosts share a SAN, configure a diagnostic partition with 100MB for each host.

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. However, if another host fails before you collect the diagnostic data of the first host, the second host will fail to save the core dump.

With the ESX host, you typically create a diagnostic partition when installing ESX by selecting Recommended Partitioning. The installer automatically creates a diagnostic partition for your host. If you select Advanced Partitioning and choose not to specify the diagnostic partition during installation, you can configure it using the Add Storage wizard.