Small Business Storage Server

Western Digital WTD-WDBLGT0120KBKS Sentinel DX4 Small Business

When embarking on a virtual server project, small-business storage needs to be seriously considered. Reliability, availability and data protection are essential features, but cost effectiveness is a key criterion too. Instead of attaching storage directly to the server, which limits your expansion options, some form of shared storage will be required.

From a management perspective, with only a small number - if any - of IT staff, a single, shared small-business storage system reduces the overheads associated with multiple storage boxes attached to different servers. Each VM can then address storage in the same way, making it easy to add, copy and duplicate VMs as necessary. And it allows VMs to share storage if required and to move between hosts. A single storage device also simplifies backup and other administrative tasks.

File or block access storage?

A key decision when selecting small-business data storage is the method of accessing data, at either the file or block level. But, as we will see, it is quite common for vendors to include both forms of access in the same device.

Block-level access allows shared storage arrays to be viewed by the server hardware and software as if they were directly attached to the server. This approach is inherently more reliable and offers higher performance. It is well suited to the random I/O and high levels of throughput that VMs demand if they are not to appear sluggish and unresponsive to end users.

Block-level storage systems can be expensive, however, and can require a dedicated storage network and associated host bus adapters (HBAs) or iSCSI adapters. Block-level storage subsystems are sometimes called storage area networks, or SANs, for reasons that don’t necessarily apply any more but it’s a tag that’s stuck.

File-level access – aka network-attached storage (NAS) - requires no dedicated network equipment, making it a more cost-effective approach more suited to small-business storage installations where performance considerations are secondary to cost or where only file sharing is required.

The traffic that busy virtual machines generate will adversely affect a production network, so to improve both performance and the security of the VM traffic, file-level storage will need a dedicated switch port to bypass production traffic.

Both file- and block-level access have pros and cons when it comes to supporting virtual server environments. After reviewing those advantages and disadvantages, you need to decide which one is best for your environment according to the likely workload, although many vendors (see survey below) sell small-business storage arrays with access via numerous block and file protocols in the same device. This are called a multiprotocol storage array, and although it incorporates both forms of access, you will need to decide whether they offer value for money according to the likely volume and nature of your storage workload.

Block protocol choice

If you opt for block storage, your choice of protocol will be determined by cost, performance requirements and your in-house skills.

Fibre Channel arrays offer the best available block-level performance. But, they’re costly and require dedicated networks (called fabrics), equipment such as HBAs and trained admins. For those reasons, Fibre Channel SANs are the preserve of larger enterprises.

The only real block access choice for smaller SMBs is iSCSI, which runs over Ethernet networks. It doesn’t necessarily need additional networking equipment - though a separate physical network can be a sensible option - and now can make use of the bandwidth of 10 Gigabit Ethernet. An iSCSI deployment needs to be well-thought-out in terms of networking and security, but the skills required are those that should be present in an organisation with existing Ethernet and TCP/IP-trained staff. iSCSI is well-supported with products for SMBs.

Some SMB storage products

Here we survey some small-business storage products. These products range from those aimed at very small businesses with so-called desktop NAS devices (although sometimes they include iSCSI access) through to SAN and multiprotocol devices aimed at the larger end of the SMB sector; these devices can include Fibre Channel block access, extra ports and capacity, plus greater processing power and enterprise-level features such as data deduplication, thin provisioning, snapshots and remote replication.

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