Data storage

Increasing storage efficiency with virtualization

Small to medium-sized businesses (SMBs) typically have several servers, for example: file servers, an Exchange/mail server, a database server, possibly an intranet or SharePoint server and servers running applications specific to their businesses, with each server having its own (usually internal) storage, termed direct-attached storage (DAS).

The amount of data needing to be stored is rapidly increasing, often by at least 60% per year and sometimes much more. Healthcare organisations, especially, are seeing rapid growth in storage needs with the increased use of computer systems and digitised applications such as patient administration, messaging, medical records and medical imaging. The growth in storage, however, is usually not spread evenly across the servers.

Some servers may experience rapid growth in the amount of data stored, and others may be growing at a much slower rate. While some servers run out of storage capacity, others will have plenty of capacity to spare. Unfortunately, this unused capacity is not accessible to the servers that need it and, as storage becomes fragmented, storage management rapidly becomes a time-consuming and fraught task for overstretched system administrators.

It can also make storage much more costly than it should be; if an organisation is only effectively able to utilise a third of its storage, this effectively triples its price.

For most SMBs, systems are usually managed by a small number of administrators, who are typically generalists rather than dedicated storage administrators. Sometimes the easiest way of dealing with a server that has run out of capacity is simply to replace it with a new server with larger storage capacity, although in terms of performance and memory the existing server was quite adequate.

In the enterprise, problems such as this have typically been solved through the use of Storage Area Networks (SANs) and storage virtualization. Storage is moved away from servers onto a dedicated storage network, where it becomes a single, pooled resource that can be allocated to servers as they need it.

Storage virtualization

Storage virtualization is essentially the logical abstraction of physical storage into virtual storage. Physical disks are aggregated together into a storage pool, from which virtual disks are created. The complexities of virtualization should be hidden, so that virtual disks appear to servers just like physical disks.

Virtual disks, however, have the great advantage that they can adapt as storage requirements change. They can grow (and in some cases shrink) as capacity requirements change, and they can be protected in a range of ways that a physical disk cannot. This means that storage assets can be used much more efficiently and cost effectively, while at the same time better protecting vital data and simplifying management of storage.

With the advent of the iSCSI protocol for storage area networks, SANs and storage virtualization has become within the reach of SMBs. An iSCSI SAN can be deployed cheaply and easily, using standard Gigabit Ethernet NICs and switches, free software initiators and attractively priced iSCSI storage.

What is also vital for the SMB market is that the storage is simple and easy to configure. The StorMagic system addresses this requirement by providing virtualized iSCSI storage that can be provisioned without needing to know anything about iSCSI.

When a StorMagic SM series storage appliance is deployed, a simple six-step wizard initially configures the storage in a matter of minutes.

Typically all of the disks in the appliance will be configured as a pool of RAID 5 or RAID 6 storage, immediately providing protection against disk failures. Storage volumes can then be created and assigned to servers with just a couple of mouse clicks.

Disks become dynamically provisioned virtual disks. This means that servers can initially be assigned small disks, but as they fill up they will automatically grow and provide additional capacity. Servers with large storage requirements will automatically get more storage capacity, while servers with more modest needs will only consume what they need. Thus storage is much more effectively shared between the servers, and expensive, unused (and unusable) capacity becomes a thing of the past.

Furthermore, adding a StorMagic server does not mean replacing existing servers. Any existing server can be added to the SAN, and its data can be dynamically migrated to the StorMagic appliance. A server that has run out of DAS storage capacity can simply have its data dynamically migrated to the virtualized storage, where it can then automatically grow to create additional capacity.

Investment in existing servers is protected, and storage administration is dramatically simplified. The total cost of storage can actually reduce, while at the same time data protection improves, making a StorMagic SAN a compelling proposition for the SMB.

Chris Farey, Chief Technical Officer, StorMagic
www.stormagic.com