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Top 10 virtual storage terms of 2013

Find out which storage features and terminology were among the most searched definitions on

The year 2013 brought significant developments in the virtual storage space. The buzz around software-defined storage continued to grow with product launches such as EMC's ViPR, while VMware vSphere and Microsoft Hyper-V hypervisors added storage features. And as with any technology, the language surrounding it can evolve just as fast as the products can.

To take a closer look at the virtual storage terms IT pros want to explore further, SearchVirtualStorage compiled a list of the 10 most viewed definitions on its site. The list shows that in an increasingly virtual world, readers are keenly interested in features and technologies that can work to improve virtual server environments.

10. I/O virtualization

A common problem in virtual server environments is having input/output (I/O) resources to keep up with requests made by processors. I/O virtualization counteracts this problem by extending PCI Express pathways to more than one device, allowing I/O resources to be shared among multiple virtual machines (VMs) and physical servers.

9. Profile-Driven Storage

The Profile-Driven Storage feature was released with VMware's vSphere 5 that allows administrators to better assign applications to certain storage tiers. In virtual server environments, management and performance are two of the biggest obstacles IT pros need to overcome. Profile-Driven Storage helps by allowing administrators to define storage tiers so that when a new VM is created, it will automatically be assigned to the appropriate tier.

8. vSphere replication

Replication isn't a new concept, but in vSphere 5.0, it was updated so VMs can be replicated at the virtual level rather than the storage level. While vSphere replication is central to backup because it automates the failover of VMs to backup sites, it also eases management. Third-party applications or arrays are no longer needed for the replication process because it's built into VMware's Site Recovery Manager.

7. vStorage API for Multipathing

As one of the application programming interfaces (APIs) VMware provides, the vStorage API for Multipathing (VAMP) aids another of the main concerns in virtual server environments: I/O consumption. These APIs, introduced in vSphere 4.0, determine the I/O path between the host and storage devices. With VAMP, multiple paths are created between the hosts and storage so there's redundancy and load balancing, thereby optimizing storage I/O throughput.

6. I/O blender

The I/O blender is a problem in virtual server environments that affects performance; it occurs when multiple workloads from different VMs are sent to the hypervisor at once. Alone, these workloads would be sequential data, but under heavy workloads the data gets mixed together, creating the "blender" effect and adding latency to the environment.

5. ODX

Offloaded Data Transfer (ODX), a Microsoft storage feature, was first introduced in Windows Server 2012. ODX is used to speed up copy and move processes in SAN environments by offloading them from the server to the storage hardware. By eliminating buffering, which typically takes place during standard reads and writes, ODX is able to use fewer CPU cycles and speed up the process.

4. Virtual LUN

Logical unit numbers (LUNs) are part of the foundation of any SAN environment. Put simply, they're numbers assigned to a single disk or group of disks or partitions in a SAN so they can be addressed by SCSI, iSCSI or Fibre Channel protocols. On the other hand, a virtual LUN -- sometimes called a thin LUN -- employs the same concept, but the logical number is assigned to a virtual space instead of a physical one, and the number of LUNs created isn't limited to the amount of available space on the storage hardware.


VStorage APIs for Array Integration (VAAI) are another set of VMware APIs that offload certain tasks to the storage array rather than having them performed at the hypervisor level. This is a way to alleviate the server virtualization hardware from heavy workloads. In vSphere 4.0, VAAI worked to offload copy and write processes to the array; in vSphere 5, it was updated to include thin provisioning.

2. FlexPod

Sold by NetApp, FlexPod is a reference architecture that comes with server, storage and networking components that have been pretested to work together. The hardware and software is from different vendors, but it's not shipped as one packaged product. Once purchased, it must be configured by the customer based on the FlexPod guidelines. Cisco is NetApp's main network and server partner for FlexPods, which include validated bundles for running VMware, Microsoft, Oracle and SAP software.

1. Storage vMotion

Storage vMotion is a feature inside VMware vSphere that eliminates the need for scheduled downtime when migrating a VM from one storage system to another. Storage vMotion can serve as a migration tool off a SAN volume to a newly purchased storage system. It's also handy when taking a SAN down for maintenance and as a load balancer.

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