Windows Server 2012 R2 Storage Features

The traditional debate of hardware versus software for disk resiliency continues in Windows Server 2012 R2.

Mark October 18th on your calendar: that's the date Microsoft has named for the release of Windows Server 2012 R2 along with Windows 8.1 and System Center 2012 R2.

It really is a remarkable date when you consider the fact that Windows Server 2012 hasn't been out a full year yet. Even more remarkable are the number of new features delivered in the R2 release. A number of new storage features made the R2 cut, which should appeal to a wide audience.

To test some of the new features we were provided with a DataON DNS-1640 JBOD array containing sixteen 600 GB Toshiba SAS disks and eight 400 GB STEC SSDs. DataON also provided LSI model 9205-8e dual-port SAS controllers. We installed one of the LSI controllers in both an HP DL560 and a Dell R715 server. The key point to call out here is that these controllers just work. In fact, they're about as close to plug and play as you can get for server hardware.

Installation

Installation consists of opening the server, installing the LSI controller card, replacing the cover, connecting two cables to the JBOD array and powering everything on.

Both servers have two smallish SAS drives configured as a RAID 1 (mirrored) array to use as the system disk. After installing the preview edition of Windows Server 2012 R2 Datacenter, the disks appear in the Disk Management tool ready to be configured (see Figure 1).

Creating a Scale-Out File Server (SOFS) requires the installation of several roles, using either Server Manager or PowerShell. You need a minimum of two physical computers with access to the disk subsystem in order to create a legitimate SOFS. The word legitimate is intentional: you can actually create a pseudo SOFS using just one computer and shared VHDX files as a lab exercise, although this isn't a Microsoft supported option.

You have two options when it comes to creating a new clustered file server (see Figure 2). Option one is a basic file server for general use, which means either an SMB or NFS file share. This type of share supports data deduplication and the typical file storage use case. Option two is for SOFS, which is new to Windows Server 2012 R2 and is specifically targeted at application data. As such, it is optimized for workloads such as Hyper-V virtual disks and requires the new SMB 3.0 protocol.

Key Features

Storage tiering is one of the key features Microsoft has delivered in the Windows Server 2012 R2 release. The concept isn't a new one as many of the high-end storage vendors have had this capability in their products for some time.

It is significant, however, that this capability is now built right into the operating system. The big deal about this feature is the tight integration with all management surfaces including Server Manager and PowerShell, and the fact that it does its job with little to no user intervention.

Creating two-tiered storage requires a total of just six lines of PowerShell as in the following:

# Get physical disks available for pooling $mydisks = get-physicaldisk | ? {$_.canpool -eq $true} # Create a new tiered storage pool New-StoragePool -StorageSubSystemFriendlyName *Spaces* -FriendlyName MyTieredPool -PhysicalDisks $mydisks

# SSD Tier $ssd_tier = New-StorageTier -StoragePoolFriendlyName MyTieredPool -FriendlyName SSD_TIER -MediaType SSD

# HDD Tier $hdd_tier = New-StorageTier -StoragePoolFriendlyName MyTieredPool -FriendlyName HDD_TIER -MediaType HDD

# Create a new tiered virtual disk and enable write-back cache $vdisk1 = New-VirtualDisk -StoragePoolFriendlyName MyTieredPool -FriendlyName Tiered_Space -StorageTiers @($ssd_tier, $hdd_tier) -StorageTierSizes @(50GB, 120GB) -ResiliencySettingName Mirror -WriteCacheSize 5GB

# Lastly, initialize the virtual disk, create partition and volume and assign a drive letter Get-VirtualDisk -FriendlyName Tiered_Space | Get-Disk | Initialize-Disk –Passthru | New-Partition –AssignDriveLetter –UseMaximumSize | Format-Volume -force -Confirm:$false

When you're done you should have a new storage space named Tiered_Space as shown in Figure 3. It is worth pointing out at this point that storage tiering only works with mirrored spaces, which means you'll only have half of the total storage available. Notice this is reflected in Figure 3 in the difference between Allocated space and Used pool space.

If you look closely at the PowerShell you'll see another new feature introduced in Windows Server 2012 R2, and that's write-back cache. This new feature sets aside a portion of an SSD to use as a cache for writes to rotating disk. This helps smooth out performance hits when data is written to the disk.

A side benefit of using Storage Spaces for your reliable storage comes whenever you need to rebuild a failed physical disk. In traditional RAID systems this can take a significant amount of time. With Windows Server 2012 R2 you can expect to see those times greatly reduced due to the use of a parallel rebuild technique.

Bottom Line

One of the things you won't find in most off-the-shelf servers available from the big vendors today is the ability to use Storage Spaces right out of the box. The problem is they don't ship disk controllers capable of connecting to a JBOD array. You'll have to go with a solution as described here if you want to check it out.