Administrator Guide

NOTE: Microsoft Hyper-V Replays create a view volume on the Storage Center for each Replay.
All other Replay Manager extensions do not create a view volume for each Replay. This is a
limitation of the Microsoft Hyper-V VSS writer.
Microsoft does not provide guidelines for the number of virtual machines that can be snapped at a time
or the best interval. Most administrators will perform snapshots once a day for most virtual machines, and
more frequently on a limited number that require a tighter recovery point objective.For more information
on the specifics of the support policies for Microsoft applications when virtualized, see these links:
• Microsoft Server Software and Supported Virtualization Environments: support.microsoft.com/kb/
957006/
• Support Policies & Recommendations for Exchange in Virtualization Environments:
technet.microsoft.com/en-us/library/cc794548.aspx
Using Replay Manager with Hyper-V on Front-End SAS
• Hyper-V hosts can use either single or multipath I/O on Front-End SAS.
• Hyper-V guests (VMs) can use only single path I/O. Multipath cannot be installed. These VMs must be
gen 2. Gen 1 is not supported.
• Dell has opened a ticket with Microsoft to address this situation.
Creating Backup Sets in a Hyper_V Cluster
Virtual machines may be moved among cluster nodes for a variety of reasons. Virtual machines may be
moved manually, for example, in preparation for planned server maintenance. Virtual machines may also
be moved dynamically, for example, when the Dynamic Optimization feature is enabled in Virtual
Machine Manager. During Dynamic Optimization, the resources of each node in a cluster are monitored
to optimize the placement of virtual machines initially and during failover.
In an environment where virtual machines move often within a cluster, and where collections of virtual
machines do not consistently move together, each Replay Manager backup set should contain only one
virtual machine per CSV. This avoids the need to frequently re-create backup sets to account for the
movement of individual virtual machines.
Support of Recovery with Pass_Through Disks
As Microsoft supports the virtualization of applications like SQL Server and Exchange, more
administrators are virtualizing their application environments and using pass-through disks for data
volumes. If there are pass-through disks attached to a virtual machine, Replay Manager can be installed
on the virtual server guest to back up the data volumes for the application. Because of the abstraction
layer that is introduced in virtualizing the hardware, the only way to recover a snapshot directly back to
the virtual machine is by using the Microsoft iSCSI Software Initiator which is available as a free download
from Microsoft (for Microsoft Vista and Microsoft Server 2008 (and later), the iSCSI Software Initiator is
included with the operating system). iSCSI uses Ethernet connectivity which is readily accessible by a
virtual machine and is easy to configure both on the server as well as the storage.
VSS Error Event ID 8194
When backing up Hyper-V virtual machines, the following error may be logged in the Windows Event
Log:
Event ID 8194
Volume Shadow Copy Service error: Unexpected error querying for the
IVssWriterCallback interface. hr = 0×80070005, Access is denied.
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