Key considerations:
•
For better network performance when a child partition with iSCSI attached storage is executing in the parent
partition, choose the dual connection configuration. This is because the NIC in the parent partition is
communicating directly with the iSCSI storage system. This also allows for the leveraging of jumbo frame
support on the physical NIC in the Hyper-V parent partition.
•
For better server performance due to reduced CPU load, leverage TCP offload engine (TOE) NICs and TCP
offload cards if possible.
•
Use dedicated NICs for iSCSI traffic and do not share the iSCSI traffic with other network traffic. Dedicated
NICs ensure greater performance and throughput because other network traffic does not interfere with the
storage traffic on the iSCSI NICs.
•
For presentation of multiple LUs to the child partition over a single iSCSI interface, choose the dual
connection configuration.
•
The dual connection configuration does
not
support dynamic addition of disks to the child partition.
Storage Provisioning
Capacity and performance cannot be considered independently. Performance always depends on and affects
capacity and vice versa. That’s why it’s very difficult or impossible in real-life scenarios to provide best
practices for the best LU size, the number of child partition that can run on a single VHD and so on without
knowing capacity and performance requirements. However, several factors must be considered when planning
storage provisioning for a Hyper-V environment.
Size of LU
When determining the right LU size, consider the factors listed in Table 2. These factors are especially
important from a storage system perspective. In addition, the individual child partition’s capacity and
performance requirements (basic virtual disk requirements, virtual machine page space, spare capacity for
virtual machine snapshots, and so on) must also be considered.
Table 2. LU Sizing Factors
Factor Comment
Guest base OS size
The guest OS resides on the boot device of the child partition.
Guest page file Size
Recommended size is 1.5 times the amount of RAM allocated to the child partition.
Virtual machine files
Define the size the same as the size of the child partition memory plus 200MB.
Application data required
by the guest machine
Storage required by the application files such as database and logs.
Modular volume
migration
Smaller LUs can be migrated using Hitachi Modular Storage Migration to a broader range of
possible target RAID groups.
Data replication
Using more but smaller LUs offers better flexibility and granularity when using replication
within a storage system (Hitachi ShadowImage® Replication software, Hitachi Copy-on-
Write Snapshot software) or across storage systems (Hitachi TrueCopy® Synchronous or
Extended Distance software).
Number of Child Partitions per VHD LU, per RAID Group
If you decide to run multiple child partitions on a single VHD LU, understand that the number of child partitions
that can run simultaneously on a VHD LU depends on the aggregated capacity and performance requirements
of the child partitions. Because all LUs on a particular RAID group share the performance and capacity offered
by the RAID group, Hitachi Data Systems recommends dedicating RAID groups to a Hyper-V host or a group
of Hyper-V hosts (for example, a Hype-V failover cluster) and not assigning LUs from the same RAID group to
15
