Planning for Hyper-V: PowerVault™ MD3200 and MD3200i Series of Arrays
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secondary RAID controller module are ignored until the ownership changes. The basic assumption for
the round-robin policy is that the data paths are equal.
Least Queue Depth with Subset
The least queue depth with subset policy is also known as the least I/Os or least requests, policy. This
policy routes the next I/O request to a data path that has the least outstanding I/O requests queued.
For this policy, an I/O request is simply a command in the queue. The type of command or the number
of blocks that are associated with the command are not considered. The least queue depth with subset
policy treats large block requests and small block requests equally. The data path selected is the path
group of the RAID controller module that owns the virtual disk.
Least Path Weight with Subset
The least path weight with subset policy assigns a weight factor to each data path to a virtual
disk. An I/O request is routed to the data path with the lowest weight value to the RAID
controller module that owns the virtual disk. If more than one data path to the virtual disk has the
same weight value, the round-robin with subset load-balance policy is used to route I/O
requests between data paths with the same weight value.
Additional Considerations for Virtual Storage
You can assign physical storage to a virtual machine in various ways. For the Dell PowerVault™ MD3200
or MD3200i storage array, you have two options:
• Assign the virtual disks to the parent server, and create a file system and a virtual hard
drive (VHD) for the virtual machine.
• Assign an unformatted physical disk directly to the VM (pass-through physical disk).
With the Dell PowerVault MD3200i storage array, in addition to the previously mentioned two options,
you have a third option: You can assign a physical disk directly to the VM by installing the iSCSI
software initiator on the VM as you would on a physical server.
Figure 5. Virtual Storage Configuration
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