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Last modified on 7/20/2016 9:22 AM by User.

Infrastructure Discussion - SANs

This document contains basic information about implementing a Storage Area Network or “SAN”. Since SAN implementations vary greatly, it is our hope that this document will allow a business executive to have a basic understanding of how the SAN works and how one might be implemented to provide company personnel with a better OASIS user experience.

Background

This document was created to give a high level understanding of how a SAN can be implemented in an environment due to the lowering cost and overall benefits of a SAN. However, if not implemented properly, the result may be less than satisfactory for OASIS users.

What triggered this document was a number of customers complaining about OASIS performance issues after a hardware upgrade. What was not considered during the sales and implementation of the SAN was the overall system architecture and impact on the OASIS relational database. Even expert SAN specialists comment that SAN implementations are only about 50% satisfactory for customers. The satisfied customers often spent the time and money evaluating, testing and working through required upgrades to network switches and other hardware.

What is a SAN?

A Storage Area Network (SAN) can be thought of simply as a box of hard drives. One problem resolved by SAN implementations concerning OASIS is long-term availability through implementation of the following features:

  • Addition of new hard disk storage while the system is running
  • Enterprise backup solutions
  • Migration to new servers with minimal downtime
  • A large pool of drives may be shared between applications, allocating drive space as needed
  • Some SANs utilize SSD (solid state storage) to boost the drive performance.

Differences in Architecture

A traditional server has all the hardware components in the same cabinet. Connecting the hard drives (and not shown) is a hard drive controller card that is capable of quickly and independently accessing each of the hard drives in the server. The access speed is only limited by the “spindle speed” or rate of disc rotation.

The SAN moves most if not all the hard drives from the server’s cabinet to the SAN cabinet(s). For small business implementations, the connection from the servers to the SAN is accomplished over a network switch. Although more expensive, fiber optic connections are possible for optimal transfer speeds.

Issues we have seen with SAN implementations

The biggest issue with the implementation of a SAN is all the hidden costs:

  • Typically the servers are virtualized, triggering a cost to virtualize the servers.
  • Current, up to date hardware is required to utilize large packet transfers across the network.
  • The network and switch MUST BE EVALUATED! This is not just a 1 Gb/s switch requirement – it must be an advanced switch.
  • Don’t use old cables. Ensure new ones are used.
  • All this is rack mounted, often triggering a purchase of a server rack.

 Also included in the cost is skilled labor. Designing, implementing, and monitoring an advanced SAN setup is not for a part-time person (or as an added duty for someone in the office).

Recommendations

  • Virtualize the servers using VMware or Hyper-V.
  • Add RAM to the server. RAM has become a cheap way to increase performance.
  • Update the server to include at least a dual NIC card. (Quad is better.)
  • Plug both the server and SAN into the same switch.
  • Upgrade the switch to a managed switch (VERY IMPORTANT).
  • And pair the NIC cards for the server and another pairing for the SAN.
  • 1 Gb/s speed is assumed. 10 Gb/s network speed is better.