Virtual data storage

The IT and mobile data revolution in the police service has led to ever-increasing demands on data storage. iSCSI storage technology could provide a flexible virtualisation solution – and help keep budgets down – argues Tim Sherbak, senior manager of virtualisation solutions marketing at Dell.

According to Gartner, virtualisation will have the greatest impact on IT infrastructures and operations over the next five years. In particular, an increasing number of enterprises are building flexible storage infrastructures using Internet SCSI (iSCSI) and advanced virtualisation technologies.

The advent of iSCSI, a flexible and powerful storage area network (SAN) protocol has enabled breakthrough virtual storage designs that parallel the advanced designs of server virtualisation technologies.

It allows organisations to consolidate storage into data centre storage arrays while providing hosts (such as database and web servers) with the illusion of locally-attached disks. Unlike fibre channel, which requires special-purpose cabling, iSCSI can be run over long distances using existing network infrastructure.

There are three simple reasons why more enterprises of all sizes are choosing to implement iSCSI storage arrays: scalability, simplified storage management and cost.

iSCSI protocol enables the implementation of advanced storage virtualisation technologies where storage is virtualised at the storage device level. This approach helps achieve scalable performance and capacity, while reducing overall management by aggregating multiple controllers into a cooperating set of resources by virtualising volumes not only across disks within a controller, but also across storage systems in a SAN.

Such ‘scale-out’ designs are virtually nonexistent in the fibre channel SAN world due to the inherent architectural constraints in fibre channel network deployments.

An iSCSI storage architecture is particularly appealing in a virtualised server environment because the scale-out architectures of both server and storage infrastructures complement each other, providing an end-to-end virtualised infrastructure.

A virtualised server and storage environment is particularly adaptable to changing business requirements by providing non-disruptive workload migration and balancing across all physical server and storage resources. Complementary server and storage virtualisation built on iSCSI SANs creates a pool of physical resources – one that provides higher performance, scalability and flexibility compared to classic storage array infrastructures.

Another benefit of an iSCSI system is that it simplifies storage management. In an iSCSI SAN, a storage group of multiple arrays appears to server systems as one entity, offering network storage access to a single, large pool of storage.

And unlike a conventional SAN where multiple controllers appear as independently managed islands of storage, each group member can cooperate with other group members to resource provisioning and performance optimisation.

Administrators can create data volumes from within the storage pool. Storage groups can use multiple storage tiers contained within the storage pool and automatically optimise data placement based on workload. As new resources become available, the resources can be automatically applied where and when they are needed.

This scalability model allows for automated, online expansion across storage dimensions, helping to eliminate downtime caused by expanding or managing a storage system. Storage is simply managed with a click of a button.

Finally, the acquisition, implementation and operational costs of an iSCSI SAN are substantially lower than those of a fibre channel-based SAN. An iSCSI SAN can be up to 50 per cent less than a traditional SAN. As a result, iSCSI SANs not only remove the cost barrier of classic SAN architectures but also the economic barrier to the adoption of virtualisation technologies.

Virtualised iSCSI-based SANs are changing expe