M5 - Lesson 3: Configuring storage on Hyper-V host servers (Considerations…
M5 - Lesson 3: Configuring storage on Hyper-V host servers
Virtual hard disk formats
A .vhdx file can be as large as 64 TB.
The .vhdx file structure minimizes the chance that a disk will become corrupted if the host server suffers an unexpected power outage.
The .vhdx format supports better alignment when deployed to large-sector disks.
A .vhdx allows larger block sizes for dynamically expanding and differencing disks, which provides better performance for these workloads.
This format is a type of virtual hard disk that multiple virtual machines can access simultaneously for high availability with clustering.
Original generation of .vhdx
Virtual hard disk types
This type of virtual hard disk allocates all of the space immediately. This minimizes fragmentation, which, in turn enhances performance.
This type of virtual hard disk allocates space as required, which is more efficient because there is no blank space in a virtual hard disk. If the virtual hard disk is .vhdx formatted and dynamically expanding, then it can also dynamically shrink when you remove data.
This type of virtual hard disk provides direct access to a physical disk or Internet SCSI (iSCSI) logical unit number (LUN).
This type of dynamically expanding virtual hard disk stores data that has changed when compared to a parent disk. Differencing disks are typically used to reduce data storage requirements.
Considerations for virtual hard disk formats and types
In the past, only fixed-size virtual hard disks were suitable for production. However, for .vhdx- formatted virtual hard disks, dynamically expanding virtual hard disks offer almost the same level of performance and are supported for production workloads.
Dynamically expanding virtual hard disks show the free space available based on the maximum size specified for the virtual hard disk, rather than the actual physical space available.
You can move a parent virtual hard disk, but you must relink it with the differencing disk.
You can link multiple differencing disks, but, as the number of linked disks increases, performance tends to decrease.
Unless you are creating virtual hard disks that must be accessed on Windows Server 2008 or Windows Server 2008 R2, you should use .vhdx-formatted virtual hard disks.
If you modify a parent virtual hard disk, a differencing disk is no longer valid.
Fibre Channel support in Hyper-V
You must configure the Hyper-V host with a Fibre Channel host bus adapter (HBA).
The Fibre Channel HBA must have a driver that supports virtual Fibre Channel.
The virtual machine must support virtual machine extensions.
Where to store virtual hard disks?
High-performance connection to storage:
You can locate virtual hard disk files on local or remote storage. When you locate them on remote storage, you need to ensure that there is adequate bandwidth and minimal latency between the host and the remote storage.
The volume on which the virtual hard disk files are stored should be fault-tolerant. This is regardless of whether the virtual hard disk is stored on a local disk or on a remote SAN device.
The storage device on which you store virtual hard disk files should have excellent input/output (I/O) characteristics. Many enterprises use hybrid SSD drives in RAID 1+0 arrays to achieve maximum performance and redundancy.
Adequate growth space:
If you have configured virtual hard disks to grow automatically, ensure that there is adequate space into which the files can grow.
Storing virtual machines on SMB 3.0 shares
SMB 3.0 is available in Server 2012 and later
Supported Hyper-V File Types
Virtual hard disks
Scale-Out File Server
Provides highly available file shares
Has storage QoS policies