Virtual storage connected by iSCSI offers datacentre managers the most cost-effective way of coping with ballooning enterprise storage requirements, according to Dell.

Enterprises are facing an ever increasing requirement for storage because of data retention policies and growing use of digital media files, according to computer giant Dell. At the same time, recent trends such as the move towards virtual machines are complicating the way storage is utilised, leading to headaches for IT departments trying to manage and stay on top of their storage needs.

Dell believes that storage virtualisation is going to play an important part in addressing this issue, and that a key part of providing this capability will be better storage area network (SAN) technology based on iSCSI. This is not perhaps surprising, as Dell is now the leading global iSCSI supplier, according to figures from analyst firm Gartner, following its acquisition of storage vendor EqualLogic earlier this year.

IT managers are familiar with the fact that the volume of storage required on their network continually grows, especially as there is a need to retain certain kinds of information for future reference as well as regulatory compliance reasons. Digital media files such as photos are also adding to the burden as these tend to be large in size.

Within a corporate environment, three types of information currently tend to occupy the lion’s share of storage allocation, Dell said. Email takes up 26 per cent on average, with files and shared storage using up another 20 per cent, while backup and protection of vital information accounts for a further 11 per cent.

The growth in storage also brings complexity, according to Dell, which estimates that 70 per cent of enterprise investment in storage is going on “just keeping the lights on”, a situation that the company is aiming to address using future products from its EqualLogic storage division.

“We want to change this situation and flip it around,” said Robin Kuepers, head of storage marketing for Dell in Europe, the Middle East and Africa, adding that customers wanted to spend more on innovating, and “want help to slow storage growth”.

Deploying iSCSI is one way to simplify storage, Kuepers said, pointing out that this protocol runs over standard Ethernet infrastructure, something that enterprises already have and are comfortable managing. In contrast, a Fibre Channel SAN requires costly dedicated infrastructure.

While iSCSI is often seen as an entry-level solution, there is increasing corporate interest in the technology because it easily scales up, Kuepers said. He said that because iSCSI boxes typically come with Ethernet ports built in, adding more storage adds bandwidth to the storage array at the same time.

Another trend that will worsen storage management headaches within datacentres is server virtualisation. This is employed to make the most efficient use of modern hardware, which is often capable of handling several virtual servers simultaneously. However, virtualisation can complicate backup and recovery operations, according to Praveen Asthana, enterprise storage director at Dell.

This is because virtual machines in a SAN-based VMware implementation are typically stored in a VMFS cluster file system configured as a logical unit number (LUN). If a snapshot is taken of the LUN, this creates a backup of all the virtual machines within it, making it difficult to roll back just one of the virtual servers if the need arises.

With iSCSI, data sets can be configured and accessed as individual LUNs, according to Dell, which makes recovery as simple as un-mounting the virtual machine from its disk volume, rolling it back to an earlier snapshot, then re-mounting it.

Forester Research senior analyst Andrew Reichman wrote in a report earlier this year that “iSCSI is inherently more virtualised than Fibre Channel, allowing for more granular addressing, especially important for virtual server environments”.

Another problem that enterprises currently face is that data is distributed here and there around the network, on numerous different servers and often on client systems as well.

“Organisations don’t know exactly how much storage they have. They know where their big databases are, but don’t know how many PCs they have, or what information is on them,” said Tony Lock of analyst firm Freeform Dynamics.

According to John Joseph, Dell vice president of storage marketing, this has led to storage “islands” as new workloads are deployed onto separate physical servers with their own local storage. This situation is inefficient, as most of this local storage is under-utilised and difficult to manage, he explained.

Not surprisingly, Dell believes the solution is for companies to separate servers from their storage and put it onto a SAN, effectively consolidating all storage into the datacentre. Previously, implementing a SAN would have been a costly investment, but Dell claims that iSCSI now makes it possible to build a SAN for less than £5,000.

One of the reasons for this is the falling cost of 10 Gigabit Ethernet (10GbE), which is increasingly being used for iSCSI storage arrays. Praveen Asthana also said that Ethernet will scale to offer greater bandwidth than rival technologies in future.

“Fibre Channel went from 2G to 4G, and there are plans to offer 8G, while Ethernet is on 10 gigabits today and there are plans for 40,” he said.

Joseph said that with Dell’s EqualLogic kit, companies can build a virtual storage environment, one where administrators can manage a pool of storage instead of individual storage devices. This pool can simply be expanded as necessary by adding extra iSCSI equipment as required.

One existing feature of EqualLogic’s kit is its support for a tiered storage architecture. Logical storage volumes are sliced up and the blocks distributed across the virtual storage array, and can also be moved around as necessary, depending on how often the data in them is accessed.

Joseph said that Dell plans in future to offer the same capability for virtual machine images, but declined to give a timeframe for this move.

“In future, we will be able to move a virtual machine to storage with a better quality of service if necessary,” said Joseph. This means that virtual machines ­ servers or desktops ­ with a heavy workload can be moved automatically to faster storage hardware.

Conversely, virtual machines that are less critical will be migrated by the storage management system to slower storage, according to Joseph, from 15,000RPM disk arrays to 10,000RPM, for example.

“You’ll be able to automatically move less frequently accessed data from $9,000 per terabyte storage to $3,000 per terabyte storage,” he said.

According to Dell, this will take some of the burden of management away from the IT staff, and go some way towards helping tackle the problem of the ongoing growth in storage.

Lock said that this kind of feature will become more prevalent in the future.

“Apart from the biggest organisations, most companies do not have dedicated staff to manage areas such as storage,” Lock said, adding that in future storage will be based on virtualisation and become much more flexible.

“Tiered storage is going to happen, but there’s a desperate need for data discovery tools, and automatic classification of data,” he said.