This buying guide gives storage managers product specifications to help them evaluate and purcahse SAN upgrade products. Let's start by listing the core concerns for any storage manager embarking on a SAN upgrade.
Set objectives for the upgrade. Once you determine the problem, you should set an upgrade goal. It's not enough to simply "add more bandwidth" to overcome a bottleneck; you should know how much additional bandwidth is really and then factor in adequate "headroom" to accommodate future growth. Setting a measurable goal makes it easier to gauge the upgrade's initial success and compare your estimated growth to the SAN's actual growth demands over time, allowing better estimates in the future.
Suppose you currently manage 10 TB of storage, which has been growing 50% each year. Your storage upgrade objectives may be to add another 5 TB of storage this year and budget another 8 TB of storage for the year after. Breaking up an upgrade into quarterly acquisitions can help ease the burden of huge capital expenditures.
Look beyond the lowest price. Rather than opting for the least expensive upgrade, consider the best "effective" price for a product that addresses all of your needs, but omits the unnecessary bells and whistles. Consider also costs incurred after the initial purchase -- usually in product service or software support. You should seek ways to reduce the cost of your ongoing service and maintenance fees as well as ongoing software support. Look at products that offer longer warranties; even going out five years if you think you'll use the technology for that long. For example, an attractively-priced storage array may require an extra software purchase (and annual license) to support snapshots. A more expensive storage array may be a better deal because it includes snapshot functionality.
The impact of technology cycles and future redeployment options. When selecting a SAN upgrade, consider potential avenues of redeployment for any products that are being displaced. Even if you have to perform a forklift upgrade, the older array being replaced may still serve the organization as a lower storage tier, storage in a remote office or disaster recovery facility, or as a lab testing platform.
Upgrades usually cost less over time. Overall storage costs (e.g., disk costs) are declining by roughly 10% each quarter. This rate of decline creates a dilemma for administrators because any savings on purchases today (even volume purchases) are generally offset by lower future costs. As a rule, don't buy today what you can buy tomorrow at a lower cost. Smaller and more frequent upgrades tend to be more cost-efficient, but you'll need to knowl growth rates and predictability to leverage this principle properly.
Interoperability and heterogeneity. Although interoperability is improving in the storage industry, you still need to ensure that the upgrade will fit smoothly with your existing SAN hardware and software. A new SAN switch must work with your current management software tools; a new array should be supported by your replication or virtualization software. Try to avoid upgrades that increase the number of tools needed to manage the storage environment.
Service and support. You may require service and support agreements for the new disk arrays or new storage management software tools. For new hardware, service and support ensures that timely technical assistance is available to restore physical failures in the storage system. For new software, service and support typically provides access to phone support and patches/updates. Some level of service and support is normally included with the initial product purchase, but renewed coverage can be costly. Make sure that service and support are available for the expected service life of your SAN upgrade. Add the cost of any extended coverage to the total cost of any upgrade plan.
Changes to management requirements and processes. Storage practices often rely on documented procedures to ensure consistent day-to-day operations. Any time hardware is added or replaced, and each time management software is revised or changed, established practices will be impacted. When considering a SAN upgrade, it's important to evaluate how those changes will influence internal IT processes.
Training needs. Major SAN upgrades may involve dramatic hardware replacement, and substantial hardware changes may demand additional IT staff training. Determine whether training is needed, the number of staff that require training and the cost of training from the product vendor. Training may be included with the upgrade's purchase price, but not always. Any training costs should be figured in the total cost of any upgrade plan.
This was first published in March 2008