TCO analyses assess the costs to acquire, deploy, operate, and manage a technology over time. A cost analysis comparison between network-attached and server-attached storage shows the value proposition of networked storage, and how management and operational costs can be minimized through the strategic implementation of the appropriate storage technology.
Server-Attached Storage (DAS) TCO Analysis
An increase of storage capacity with DAS means that more drives must be added to an existing server or another general-purpose server with attached storage must be purchased.
Cost of acquisition -- the price per megabyte is relatively low, so the costs of adding additional drives or an additional server are usually reasonable.
Cost to deploy - deploying server-attached storage often incurs a hefty downtime penalty. The server must be configured with the operating system, storage management applications and network connections. The disk array must be configured for host operating system access and for volume sharing across a LAN using network file systems such as NFS or CIFS. Complex storage arrays can require more than a day for these processes, resulting in downtime and lack of storage availability for the same period of time.
Cost to manage -- managing server-attached storage configurations usually require more IT staff, or a proprietary suite of storage management software. Consequently, in many companies,
Cost to operate -- High-availability solutions for server-attached storage typically require clustered servers and storage interconnects that can be difficult to maintain and operate, and costly to acquire and deploy.
Network-attached storage (NAS) TCO Analysis
Network-attached storage (NAS) easily addresses the TCO drawbacks of server-attached storage.
Cost of acquisition - NAS appliances are essentially disk arrays combined with a kernel operating system optimized for network connectivity and storage. With most NAS servers, the acquisition cost is comparable to a server-attached storage configuration of the same capacity.
Cost to deploy - NAS does not require connection to a server HBA. It connects directly to a network. Deployment of NAS can be ?plug-and-play? with common IP services such as the Dynamic Name Service (DNS). NAS servers usually come pre-configured to support NFS and CIFS and typically require only a few minutes of configuration. In the most complex instances, additional configuration steps may be required (e.g., to create virtual volumes or to customize RAID configurations). However, these steps are usually performed offline and before device installation. No downtime is associated with deployment of a network-attached storage appliance.
Cost to manage - Most NAS servers feature their own management utilities. Many products can also be monitored and managed via standard SNMP-based network management systems already in use. In short, NAS deployments do not require additional IT personnel skills or new storage management programs.
Cost to operate - Without a general-purpose operating system, NAS products have fewer components to fail and fewer reasons to go offline. High-availability configurations enable continuous access to data, even in the event of a disk failure or other disruption.
The current trend toward networked storage speaks to the widespread acknowledgement of the need for a solution that scales beyond the confines of server-tethered storage, and can adequately address TCO issues.
About the author: Page Tagizad is the Director of Product Marketing at Procom Technology.
This was first published in August 2001