Enterprises that have enjoyed virtualization’s benefits in their test/development environments have long wanted to use it in their production systems. But until recently, many small and medium-sized businesses have been put off by the cost and complexity of connecting virtualized servers to storage area networks.

Virtualization adds challenging new demands to managing fibre channel SANs, which are already complicated to administer and expensive to implement.  Companies that wanted a robust and flexible storage environment for their virtualized servers needed to address the difficult and tricky array of problems that fibre channel networks presented.

When VMware announced late last year that it would support iSCSI networks, other virtualization technology providers followed suit, and the landscape changed almost overnight.  With iSCSI connectivity, enterprises of all sizes can confidently exploit the advantages of virtualization without the expense, complexity and risks of using a fibre channel network.

Simpler Storage Deployment and Management

Virtualization requires that enterprises implement a shared back-end storage environment.  iSCSI networks not only are much less expensive than fibre channel, but they are also much simpler to deploy and manage.  In fact, the benefits of iSCSI are especially apparent when virtualization is employed.

With virtualized environments, iSCSI simplifies managing the connection between servers and storage.  iSCSI networks use the storage functionality that resides in every virtual machine to establish a direct, unique relationship with the target storage array.  iSCSI technology streamlines the management of data-intensive workloads and delivers full application functionality and robust data protection.

Fibre channel networks require IT administrators to first allocate storage and assign it to a hypervisor (the operating system of the physical platform hosting a virtual machine), then configure the hypervisor to grant the virtual machine access to that storage system. 

Known as arbitrated storage, this process is not only complex, but also poses a threat to data integrity. Every physical device that hosts a virtual machine has access to storage, so if a process runs awry, it can overwrite or otherwise corrupt valuable data.

To provide virtual machine mobility, all fibre channel ports must be open to all VMs, which also increases the possibility of data corruption. Moreover, every time a new virtual machine is brought online, the administrator must first define storage on the target array and then configure the hypervisor, a multi-step process in which mistakes can have real consequences..

Familiar and Standards-Based

iSCSI networks combine the simplicity of IP protocols for networking and SCSI commands for storage to deliver a simple and affordable disk storage solution to the virtualized datacenter. An iSCSI network connects host servers (initiators) to remote storage devices (targets), which appear as local hard drives.  Unlike fibre channel networks, which use expensive interfaces and switches and require extensive knowledge to manage, iSCSI SANs use familiar IP commands and standardized Ethernet interface cards, switches and routers.

While fibre channel is commonly believed to deliver the best performance, in actual practice iSCSI delivers comparable speed with most applications. Because so many key applications have random I/O patterns, performance is usually more affected by read-write operations to disk than by bandwidth limitations.

After surveying more than 500 companies, the Enterprise Strategy Group found that “iSCSI SAN early adopters have not experienced any performance issues”.  In any event, the advent of 10 Gigabit Ethernet promises to enable iSCSI networks to deliver faster performance than fibre channel in the near future. 

Less Room for Error

Because administrators using iSCSI assign storage directly to the virtual machine without having to configure the hypervisor, data integrity and availability are better ensured.  “Simply put, direct storage has less room for error, is faster to set up, and is far easier to manage,” says Matt Baker, storage product manager at Dell.  “It greatly simplifies the process of dependably connecting virtualized servers to storage systems while achieving data integrity and availability.”  

Finally, iSCSI networks deliver seamless virtual to physical application migration—any application or image developed on a virtual machine will transfer to a non-virtualized server; with fibre channel, testing applications and additional coding are frequently required.

Dell: Leading the Way with iSCSI and Virtualization

Dell has partnered with EMC and VMware to deliver world-class virtualization solutions, including the CX3-10, an entry-level SAN array that supports iSCSI and fibre channel, enabling customers to create a tiered, high-performance storage environment.   Dell is committed to iSCSI as a key technology for reducing the cost and complexity of storage, while delivering availability and data protection.

Dell designed its iSCSI product portfolio to help customers optimize their storage environment to best meet their business needs:

• Multi-protocol, purpose-built SAN arrays with simplified management features
• Ideal for consolidation and second-tier storage with virtualized servers
• Dell CX3-series support both iSCSI and Fibre Channel connectivity
• Delivers complete non-virtualized functionality to virtualized environments
• Seamless integration of virtualization with an optimized storage environment

Dell also provides storage area networking and virtualization planning, implementation and support services to help you throughout the IT lifecycle.