vSphere Storage - ESXi 5.1 - Documentation - VMware

Set Up Dynamic Disk Mirroring
Typically, you cannot use logical-volume manager software on virtual machines to mirror virtual disks.
However, if your Microsoft Windows virtual machines support dynamic disks, you can protect the virtual
machines from an unplanned storage device loss by mirroring virtual disks across two SAN LUNs.
Prerequisites
n Use a Windows virtual machine that supports dynamic disks.
n Required privilege: Advanced
Procedure
1 Create a virtual machine with two virtual disks.
Make sure to place the disks on different datastores.
2 Log in to your virtual machine and configure the disks as dynamic mirrored disks.
See Microsoft documentation.
3 After the disks synchronise, power off the virtual machine.
4 Change virtual machine settings to allow the use of dynamic disk mirroring.
a Right-click the virtual machine and select Edit Settings.
b Click the VM Options tab and expand the Advanced menu.
c Click Edit Configuration next to Configuration Parameters.
d Click Add Row and add the following parameters:
Name Value
scsi#.returnNoConnectDuringAPD True
scsi#.returnBusyOnNoConnectStatus False
e Click OK.
Creating a Diagnostic Partition
To run successfully, your host must have a diagnostic partition or a dump partition to store core dumps for
debugging and technical support.
Typically, a local diagnostic partition is created during ESXi installation. You can override this default behavior
if, for example, you use shared storage devices instead of local storage. To prevent automatic disk formatting,
detach the local storage devices from the host before you install ESXi and power on the host for the first time.
You can later create a diagnostic partition on a local disk or on a private or shared SAN LUN using the client.
The following considerations apply:
n A diagnostic partition cannot be located on an iSCSI LUN accessed through the software iSCSI or
dependent hardware iSCSI adapter. For more information about diagnostic partitions with iSCSI, see
“General Boot from iSCSI SAN Recommendations,” on page 119.
n Unless you are using diskless servers, set up a diagnostic partition on a local storage.
Chapter 17 Working with Datastores
n Each host must have a diagnostic partition of 110MB. If multiple hosts share a diagnostic partition on a
SAN LUN, the partition should be large enough to accommodate core dumps of all hosts.
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