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Microsoft Corp. revealed its forthcoming Windows Server 2012 R2 at this month's TechEd conference. Although a preview build won't be available for download for a few weeks, Microsoft has given us a tantalizing glimpse into what we can expect from the new operating system.
As you probably know, the original Windows Server (WS) 2012 release was jam-packed with hundreds of new features, the bulk of which were related to storage and virtualization. Microsoft's Windows Server 2012 R2 continues this trend by focusing on improvements to the storage subsystem and server virtualization.
Native tiered storage feature
With regard to storage, the biggest improvement in WS 2012 R2 is the inclusion of a native tiered storage feature that's an enhancement to Windows Storage Spaces. The idea behind this feature is that if an administrator adds both solid-state drives (SSDs) and hard disk drives (HDDs) to a storage space, the storage space engine will automatically differentiate between the two types of storage. In doing so, Windows will move hot blocks (blocks of storage that are read more frequently than other storage blocks) to SSD storage, while cooler blocks will remain on HDD storage. Remember, there's a very distinct trade-off between SSDs and HDDs. While SSDs are very fast, they're expensive and have comparatively low capacities. On the other hand, HDDs have plenty of capacity and are relatively inexpensive, but don't offer the performance of SSDs.
The storage tiering feature should greatly boost read performance on Windows servers. This will be especially true for servers acting as virtual desktop infrastructure (VDI) hosts, since VDI images are often identical to one another and share many common storage blocks when deduplicated.
The nice thing about storage tiering is that it will be simple to implement. Although this could potentially change by the time Windows Server 2012 R2 is released, the current build provides the option to create a storage tier within the New Virtual Disk Wizard. When an administrator creates a virtual disk, he can select a checkbox to enable storage tiering for the virtual disk. If storage tiering is enabled, the movement of hot and cold blocks between SSD and HDD storage becomes automatic. Furthermore, the option to tier or not to tier storage for individual virtual hard disks (VHDs) means you won't waste valuable SSD resources on VHDs for which performance isn't a high priority. Microsoft even provides an option to specify the size of each tier on a per-virtual disk basis.
WS 2012 R2 can also use SSDs for persistent write-back caching. The idea here is that write operations can be cached to an SSD and then later written to HDD storage. This can help to improve overall storage performance.
Microsoft is offering some new fault-tolerant options. A dual parity option now creates a logical disk structure that is similar to RAID 6. There's also an option in the New Virtual Disk Wizard to create a three-way mirror.
One of the big draws of Windows Server 2012 was native deduplication that could be applied on a per-volume basis without the use of third-party software. However, Microsoft placed a number of restrictions on the types of volumes that could be deduplicated. More importantly, Microsoft stated that Hyper-V hosts and VDI virtual hard disks weren't good candidates for deduplication.
WS 2012 R2 supports running virtual machines (VMs) on deduplicated storage. It's common for VMs to share a common set of storage blocks and, because deduplication tracks the location of storage blocks, VM performance generally improves when the underlying storage is deduplicated. For example, in a demo shown during the opening keynote at TechEd, five VMs were booted from non-deduplicated storage while an identical set of VMs was booted from deduplicated storage. The VMs booting from deduplicated storage booted in less than half the amount of time than their counterparts.
As you can see, Windows Server 2012 R2 offers some promising enhancements to storage management. Features such as storage tiering and new fault-tolerant mechanisms should provide SAN-like capabilities to organizations that don't have a SAN.