Special cases and exceptions

The Volume Shadow Copy Service and Virtual Disk Service offer the option to choose the storage protocol.

You are responsible for ensuring that changing the storage protocol and Volume Shadow Copy Service and Virtual Disk Service settings for VMware does not affect the previously created snapshots.

Example of a special case that causes problems

This example illustrates a special case that can cause some problems. The procedure in this example is as follows:
  1. Create a snapshot with the FC protocol.
  2. Change the protocol setting to virtual machine iSCSI.
  3. Incorrectly modify or clear the VMware settings.
  4. Delete the previous created snapshot.

In this case, the FlashCopy® map is removed on storage and the target LUN is unmapped from the hosts. However, the RDM file remains on the ESX(i)(i) Server because the VMware settings (vmhost, vmuser, vmpassword, or vmcredential) were incorrectly set. This leaves the Volume Shadow Copy Service and Virtual Disk Service unable to communicate with the ESX(i) Server.

If the VMware settings are correct, the deletion process can still be successful with the RDM file removal.

If this example case occurs, a warning message displays when the user tries to change the VMware settings using ibmvcfg.

It is not necessary to configure the Volume Shadow Copy Service and Virtual Disk Service parameters (such as vmhost and vmuser) for VMware. If you decide to use the virtual machine software iSCSI protocol, all processes are run using Ethernet protocol.